| Date Answered | Questioner (age, location) | Question | Answer |
|---|---|---|---|
| October 9, 2008 | Jayden (age 10, Alabama) | What is the difference between a savanna and a grassland? | There are several types of grassland. They are distinguished by different names like plains, prairies, savannas and pampas. MOre information in our web page Grassland Ecosystem. |
| October 9, 2008 | fara (age 15, malaysia) | what is it mean by 'aurora',the northern light?what cause it?sunlight or earth magnetic field? | The auroras are a beautiful manifestation of the link between space and our planet. The aurora is formed when protons and electrons from the Sun travel along the Earth's magnetic field lines. These particles from the Sun are very energetic causing the gases of the atmosphere to light up like the gases of a streetlamp! More information on our web page Auroras. |
| October 7, 2008 | vishal (age 20, india) | let us suppose that the core of the earth stops rotating...then will it stops the rotation of the earth | It could, eventually, due the viscosity friction, but would take many years! |
| October 3, 2008 | Daisy (age 10, Philippines) | what is the blanket of the earth? | Different things could be called "blanket" of our planet. The atmosphere is Earth's blanket of gases, the ionosphere (composed of ions and electrons) also works as a blanket since it absorbs some radiation. The magnetosphere (Earth's magnetic field) is our shield of many different radiations from space. |
| October 3, 2008 | Daisy Rie (age 10, Philippines) | what is the blanket of the earth? | Different things could be called "blanket" of our planet. The atmosphere is Earth's blanket of gases, the ionosphere (composed of ions and electrons) also works as a blanket since it absorbs some radiation. The magnetosphere (Earth's magnetic field) is our shield of many different radiations from space. |
| October 1, 2008 | luisa (age 13, new zealand) | why does the earth rotate around the sun? | The Earth and the rest of the planets, comets, etc. rotate around the Sun as a result of the formation of our Solar System: The Sun and the planets formed as a result of the gravitational collapse of accreting material. This material was part of the solar nebula, and transferred its rotational motion to the planets, accelerating as its radius of rotation decreases. |
| September 30, 2008 | Kaylan (age 24, AZ/USA) | How many times during the year would the sun's rays strike perpendicular in Honolulu Hawaii, Phoenix, AZ and Sorocaba, Brazil? | Outside the tropics (north of the Tropic of Cancer, 23.5° N, or south of the Tropic of Capricorn, 23.5° S), the Sun would not be directly overhead at any time during the year. Inside the tropics, the Sun is directly overhead twice each year, around March 21 (vernal equinox) and September 21 (autumnal equinox). Now you just need to look for the latitudes of those points to find the answer. |
| September 30, 2008 | chinmaye (age 12, india) | is any danger to earth if yes,how. | The most immediate danger to our planet is our own uncontrolled use of non-renewable resources, and the dumping of contaminants on soils and on the atmosphere. Climate changes, especially global warming, could seriously affect our planet. |
| September 30, 2008 | ashley (age 9, fl) | when plates move apart, what forms? | Tectonic plates pull apart at spreading ridges. |
| September 30, 2008 | KOmbe (age 17, Taxas) | How would the seasons be affected where you live if the tilt of the earth's axis of rotation increased from 23.5 degrees to 40 degrees? | There is no doubt that significant changes will affect our planet with such a drastic change on the tilts of its axis. For starters, the tropics would expand up to about 40 N to 40 S latitude, and the northern and southern temperate zones would have much more equalized temperatures. |
| September 26, 2008 | April (age 32, Utah) | Related to the orbit of the planets around the sun, if the sun can hold what is it 10000 earths, then what is DIRECTLY behind the sun in the extact same orbit as us? | Nothing. Only our planet and its moon follow this orbit. |
| September 26, 2008 | likita (age 10, georgia) | what force drives the movement of tectonic plates? | The main force that shapes our planet’s surface over long amounts of time is the movement of Earth's outer layer by the process of plate tectonics. Movements deep within the Earth, which carry heat from the hot interior to the cooler surface, cause the plates to move very slowly on the surface, about 2 inches per year. There are several different hypotheses to explain exactly how these motions allow plates to move. More information on our web page Plate Tectonics and links therein. |
| September 26, 2008 | shashank (age 19, india) | what is the rainfall conditions in cold desert | The annual precipitation in Antarctica is so low that Antarctica is really a desert, and in fact the interior parts of the continent get less precipitation every year than the Sahara dessert! MOre information on our web page . |
| September 25, 2008 | Ken (age 65, Mississippi USA) | Has the Earth always tilted or, did the flood cause it? | It is assumed by many scientists that Earths axis was tilted very early in the evolution of our planet, when a object around the size of Mars struck Earth. |
| September 24, 2008 | Chinmay (age 26, India) | The heating of the parts of the atmosphere by say ozone(absorption of UV radiation) must be balanced by a cooling process to maintain the temperature.How does tis occur? | Part of the enrgy that reaches our atmosphere is used in the production of new elements, especially at the ionosphere, that owes its existence to the UV solar rays. Some of these ions and electrons recombine later on, releasing the energy back. The atmosphere also reflects sunlight back to the space, and part of the heat is stored in the ocean and land. |
| September 15, 2008 | dani (age 20, canada) | i wanna to ask tht is it true tht in 2012 we all living beings are going to die and our earth is going to explode? | No, there is no a scientific reason for such a disaster and extinction to happen! |
| September 15, 2008 | christine (age 11, philippines) | what is an ecosystem? | An ecosystem is a region of land that has its own unique climate and life. The amount of rainfall, temperature and sunlight makes each region the way it is. Each biome is filled with plants and animals that have adapted to that land. All together, the land and its life is called an ecosystem. More information in our web page Ecosystems. |
| September 15, 2008 | christine michaela joy (age 11, philippines) | what is an ecosystem? | An ecosystem is a region of land that has its own unique climate and life. The amount of rainfall, temperature and sunlight makes each region the way it is. Each biome is filled with plants and animals that have adapted to that land. All together, the land and its life is called an ecosystem. More information in our web page Ecosystems. |
| September 11, 2008 | Antoinette (age 12, Arizona, USA) | Where in the atmosphere are satellites found? | Different satellites operate at different altitudes. For example, GPS satellites are at an altitude of approximately 20 200 kilometers, while the COSMIC satellites are at an altitude of around 750 km. In general it can be considered that the satellites are moving at the exosphere level. |
| September 10, 2008 | Janeth (age 10, Texas) | what is the lenght of orbit ("year") of the earth? | The lenght of an Earth year is 365 days 5 hrs. |
| September 10, 2008 | Janeth (age 10, Texas) | what is the lenght of the rotation ("day") of the earth? | It is generally accepted that the lenght of the day in our planet is 24 hours. |
| September 9, 2008 | Dean (age , ) | It is not my area of expertise, but I think you will find this article interesting (and supporting of your ideas). | |
| September 9, 2008 | madeline (age 9, Australia) | What happens if the atmosphere gets too thick? | Your question is to wide to answer in detail, but there are two important factors to keep in mind, possible changes in the composition, and an increase in the atmospheric pressure. |
| September 8, 2008 | mizzy (age 14, australia) | Where do the main Greenhouse gases come from? | There are natural and human-related sources of greenhouse gases, among them are industrial development, fossil fuel burning, deforestation and agricultural practices, etc. The combination of these factors have led to an increase in the atmospheric concentration of gases such as carbon dioxide and methane, the gases that are responsible for the greenhouse effect. |
| September 8, 2008 | Julian (age , ) | Hola Julian, Tu inglés es impresionante, pero te respondo en español, que es nuestro primer idioma. Argentina está casi en el borde oeste de la Placa Sudamericana, que se mueve al oeste. Al frente, sobre el Pacífico, tiene la Placa de Nazca, que interacciona con la Sudamericana en una zona de subducción, es decir, la Placa de Nazca se desliza BAJO la Placa Sudamericana. | |
| September 4, 2008 | karyn (age 16, philippines) | would you please explain to me briefly what the sulfur cycle is all about? thanks. | The sulfur cycle can be described as follows. Most of the sulfur in our planet is stored in rocks or buried deep in oceanic sediments. There also is sulfur in the atmosphere. Sulfur reaches the atmosphere through both natural (for example, volcanic eruptions, bacterial processes, evaporation from water, or decaying organisms) and human sources (mainly a consequence of industrial processes). In the atmosphere, sulfur reacts with oxygen, water or other chemicals. The particles produced react with rain and fall as acid rain. The particles will than be absorbed by plants again and are released back into the atmosphere. |
| September 3, 2008 | David (age 57, USA) | I just read an articale on www.cnn.com that says scientist are saying there is 50/50 chance that the North Pole will be ice free for a short time this September. Do you have any updated pictures of the North Pole? | This is a recent picture of the North Pole. |
| September 3, 2008 | Katie (age 23, Wisconsin) | What natural or human-related activities could raise or lower the Earth's planetary albedo? | Just an example. The releasing of particulates to the atmosphere can contribute to the formation of clouds (if they will precipate is another question). The presence of clouds affects the albedo of our planet. PLase, visite our web page Aerosols and Cloud Formation for more information. |
| September 3, 2008 | Katie (age 23, Wisconsin) | What natural or human-related activities could raise or lower the Earth's planetary albedo? | Just an example. The releasing of particulates to the atmosphere can contribute to the formation of clouds (if they will precipate is another question). The presence of clouds affects the albedo of our planet. |
| September 3, 2008 | sedew (age 22, india) | how much of earth's surface is covered by forests? | Tropical forests are restricted to the small land area between the Tropic of Capricorn (latitudes 22.5° North) and the Tropic of Cancer (22.5° South). Not long ago, tropical rainforests covered as much as 14 percent of the Earth’s land surface, but today less than 5 percent of Earth's land is covered with these forests (about 2.41 million square miles). |
| September 2, 2008 | sidney (age 22, Nigeria) | can you please sent me the website where I can find the history of the earth's revolution? | Our website Earth offers a huge amount of information on this topic. Furthermore, a simple google search brings a good number of findings. Just two examples: http://sci.waikato.ac.nz/evolution/EarthHistory.shtml http://www.geocities.com/capecanaveral/lab/2948/originoflife.html |
| September 2, 2008 | Denis (age 28, Uganda) | what is the amount of fresh water on the earth and how much is it accessible for human use? | From all the water on Earth, just about 3% is fresh water. The majority, about 69 percent out of this 3%, is locked up in glaciers and icecaps, mainly in Greenland and Antarctica. Another 30.1% is ground water, and the rest includes fresh surface water (river, lakes, swamps, etc.) |
| September 2, 2008 | Ken (age 49, MD) | Why do we not see the hottest temperatures of the northern hemisphere summer at the summer solstice? It's always hottest later, like late July/August, when I'd think it should be getting progressively cooler. | Our planet have a huge heat capacity. There is always a balancing process between what we received from the exterior, and the amount of heat energy stored near the surface in our planet. This is the reason to observe the highest temperature later. |
| September 1, 2008 | raven (age 10, india) | why is the earth compressed from its poles? | This effect is related with the spinning motion of our planet on its axis. The centrifugal force (the apparent force in a rotating system that deflects masses radially outward from the axis of rotation)increases towards the equator and decreases towards the poles. |
| September 1, 2008 | raven (age 10, india) | why is the earth compressed from its poles? | This effect is related with the spinning motion of our planet on its axis. The centrifugal force (the apparent force in a rotating system that deflects masses radially outward from the axis of rotation)increases towards the equator and decreases towards the poles. |
| August 29, 2008 | mary (age 14, phillippines) | how far earth to the sun? | For Earth: Minimum Distance from Sun: 146 million km (91 million miles) Maximum Distance from Sun: 152 million km (94.5 million miles) |
| August 25, 2008 | Tina (age 13, U.S.) | What are the names of the metals that make up the Earth's Crust? | The Earth crust is composed of thin silicate rock material. There are 90 known elements in the Earth’s crust, and they combine to form minerals (there are around 3 700 known minerals in the Earth’s crust). |
| August 24, 2008 | MANNJU (age 13, MALAYSIA,SELANGOR) | tell me about the thinning of the ozone layer. | We have several pages dedicate to this topic. If you please, you can start with our page Ozone - An Overview and follow the links therein for further information. |
| August 24, 2008 | Clare (age 10, Sydney,Australia) | How do sunspots affect the Earth's weather? | Although correlations between solar activity, global temperature, and rainfall have been observed, the link is still not clearly established, and there is no consensus among scientists as to whether sunspots actually affect the earth's weather or not. |
| August 21, 2008 | Maureen (age 57, New Jersey) | How many 1 degree latitudes are there in the northern half of the globe? | Both halves of the planet run from 0o to 90o. 0o corresponds to the equator, and 90o to the poles. |
| August 21, 2008 | Diana (age 15, new zealand) | What motion causes the movement of the moon through the sky each night ? thanks | The most visible effect of the Moon on our planet are the tides. Our web page Ocean Tides explains this effect in detail. |
| August 20, 2008 | Sara (age 19, England) | how does the earth's interior processes affect the earth's surface? | From the magnetic field that shield our planet to the plate tectonics that constantly reshape it, many characteristics of Earth are determined by proccesses in the interior. |
| August 19, 2008 | william (age 24, tennessee) | what rocks can be changed into sediment by weathering and erosion: sedimentary, igneous, metamorphic or all of them. thanks | All of them! These processes afect all kind of rocks and are an important part of the Rock Cycle. |
| August 18, 2008 | brittany (age 11, tas) | what are the polar regions? | Our website Plate tectonics and people to answer your question in detail. From there I extracted the following information, "Since the year A.D. 1600, nearly 300,000 people have been killed by volcanic eruptions." |
| August 18, 2008 | Irene (age 12, ca) | how many deaths have stratovolcanoes caused!? | To answer your question in detail would be it better to consult this page: Plate tectonics and people. From there I extracted the following information "Since the year A.D. 1600, nearly 300,000 people have been killed by volcanic eruptions." |
| August 18, 2008 | Wilson (age 13, Minnesota) | Fossil graveyards have fossilized animals, but why are the animals from different climates? | You are absolutely right! This is related to the fact that the different regions of our planet have had different climates during their geological history. For example, good part of Colorado was under the sea, and the Sahara had at some point a fresh, green climate. |
| August 14, 2008 | Tanja (age 31, Croatia) | Why is summer daylight in Helsinki longer than New York? | Helsinki latitude is 60°10' N while New York is at 40°47' N. Due to the different inclination of the Sun over the horizon, summer days are longer at higher latitudes. |
| August 14, 2008 | zeyna (age 17, australia) | what type of rock is the three sisters | The soft sandstone of the Blue Mountains is easily eroded over time by wind, rain and rivers, creating espectacular formations like the Three Sisters. |
| August 14, 2008 | Elizabeth (age 22, Free State) | South Africa has a lack in water supply & it is estimated that in a few years time,it will not have any water at all.Where are all the water in South Africa going to? | I recommend to visit the web page Water Issues to find answers to your question. |
| July 8, 2008 | stuti (age 14, india) | how many chloro fluro carbons does an air conditioner emit in 1 hour?how does the CFC's deplete the ozone layer? | Please, visit our web pages The Greenhouse Effect & Greenhouse Gases and Repairing the Antarctic Ozone Hole! for in-depth information on this subject. |
| July 8, 2008 | simran (age 10, canada) | what does the earth's layers have in them? | The core is composed mostly of iron (Fe) and about 10% sulphur (S). The mantle, which is composed of iron (Fe), magnesium (Mg), aluminum (Al), silicon (Si), and oxygen (O) silicate compounds. The crust is composed of the least dense calcium (Ca) and sodium (Na) aluminum-silicate minerals. |
| July 3, 2008 | ARIF (age 14, ENGLAND) | WHATS IS THE EFFECTS OF WATER POLLUTION ON LIVING THING | Life, at least the kind we know, is not possible without water. However, contaminated water can be extremely perjudicial to life. More information here. |
| July 3, 2008 | kembreia (age 12, las vegas) | what does the ecosystem look like? | An ecosystem is a region of land that has its own unique climate and life. The amount of rainfall, temperature and sunlight makes each region the way it is. Each biome is filled with plants and animals that have adapted to that land. All together, the land and its life is called an ecosystem. More information in our web page Ecosystems. |
| July 3, 2008 | kembreia (age 12, las vegas) | is the ecosystem changing? | Absolutely, all ecosystems are changing. This is a continuous process that can be accelerated by external factors like global warming. |
| July 3, 2008 | kembreia (age 12, las vegas) | is the ecosystem changing? | Absolutely. All ecosystems are changing. This is a continuos process, that can be accelerated by external factors like global warmimg. |
| July 3, 2008 | kitauge (age 10, louisiana) | How do location on earth and the angle of sunlight affect temperature? | At the equator (latitude = 0o) the sun rays hit the atmosphere vertically, which makes possible that most of the rays reach the Earth surface. For higher latitudes, the angle varies from 90o to almost 0o at the poles. With the smaller angles, more sun rays are reflected back to the space, and less energy reach the surface, which is the main reason for the colder climates. |
| June 30, 2008 | vainess (age 14, tanzania) | please explain more about soltice. | There are two solstices in a year, when the tilt of the Earth's axis is oriented directly towards or away from the Sun, causing the Sun to appear to reach its northernmost and southernmost extremes. In other words, solstices are the two times of the year when the sun is at its greatest distance from the celestial equator. For more information visite our web pages Summer Solstice and Winter Solstice. |
| June 30, 2008 | javockie (age 11, ms) | what is the size of the earth | Our planet diameter is 12 753 km (7,926 miles), its mass 5.98x1024 kilograms (6.521 tons), and has a density of 5 515 kg/m3. |
| June 30, 2008 | blh (age 00, california) | Why dosen't the Earth stop rotating? | Earth's angular momentum is tremendous. The amount of energy required to slow down our planet is proportional to this angular momentum. There are forces slowing down the planet, but at a very small rate. For example, Earth lost 0.63 milliseconds (0.00063 seconds) per day in the 12-month period from July to June 2001. |
| June 27, 2008 | Bailee (age 12, Utah,America) | What would happen if the Earth's magnetic pulse was stable? How can you measure it when there is pulses? | Variations on the various components of our planet's magnetic field are recorded by magnetometers distributed around the world. Many of these variations are caused by the interaction of the magnetic field with the solar wind. |
| June 25, 2008 | Travis (age 13, Texas) | how is carbon removed from the armosphere? | Carbon is removed from the atmosphere is several ways. The two most important are: Plants: Using the sunlight plants perform photosynthesis to convert carbon dioxide into carbohydrates, releasing oxygen in the process. Oceans: Near the poles, where the surface water becomes cooler, more carbonic acid is formed as CO2 becomes more soluble. |
| June 23, 2008 | Leah (age 16, Ohio/U.S.A.) | Cinder Cone Volcanoes are said to erupt only once but what keeps them from erupting more than once? | Cinder cone vlcanoes do erupt, in general, more than once. For example, since Cerro Negro volcano (Nicaragua) was born in 1850, has erupted more than 20 times, most recently in 1995. |
| June 18, 2008 | Bain (age , ) | Tornadoes can occur on any day of the year and at any hour, but the most violent tornadoes form during the spring and summer; when the strong thunderstorms that produce them are more frequent. | |
| May 28, 2008 | Vainess (age 14, Tanzania) | is the earth flat or spherical? | Since long ago our planet has been known to be espherical, and with the artificial satellites on orbit around the planet, we can now see it clearly from pictures taken by them. |
| May 22, 2008 | glady (age 14, Tanzania) | What is the name given to the earth's shape? | The Earth's precise shape is known as the geoid. It is very close to an oblate spheroid (a rounded shape with a bulge around the equator). |
| May 14, 2008 | Matt (age 12, U.S.A.) | How do humans contribute to global warming? | There are many ways in which humans affect the planet, including our contribution to global warming. One of the most drastic is the production of CO2, carbon dioxide, through industries, agriculture, and the use of fossil fuels. Please, visite our webpage Climate and Global Change for additional information. |
| May 13, 2008 | colin (age 11, florida) | What occurs when the sun is directly over the equator? | This corresponds to the equinoxes, which occur two times per year: the Autumnal Equinox (September 22nd or 23rd), and the Spring Equinox (March 20th or 21st). |
| May 8, 2008 | sharanya (age 13, karnataka(India)) | Because of gravity , why does not the earth fall on the sun? | Because it is kept in orbit by a combination of the gravitational (centripetal) force and the centrifugal force. The first one atracts the Earth, and the rest of the planets, toward the Sun, but the second one tries to force the earth to escape. A balance between them keeps the earth in place. |
| May 7, 2008 | cristina (age 11, us /florida) | what is the size of the earth ? | The diameter of our plnet is 12 753 km (7,926 miles), and it has a mass of 5.98x1024 kilograms (6.5x1021 tons). |
| May 2, 2008 | Wendy (age 33, Philippines) | Cite natural phenomena proving that the earth's interior part is very hot | Volcanoes, seismic activity, hot spots, mid-ocean ridge, etc. are manifestations of a hot core at the center of our planet. |
| April 30, 2008 | George (age 11, Macau) | What causes tides? | Due to the mutual gravitational atraction between the Earth and its moon, there are forces acting over both. In the case of our planet, the only element that can be moved is liquid, and the bigger bodies of water show the effects of this atraction in the form of tides. |
| April 29, 2008 | hunter (age 12, canada/dunnvill) | whatdo you know about Mt.Vesuvius? | There are many websites with information about Mt. Vesuvius, for example this one is very interesting. |
| April 24, 2008 | Tina (age 40, Pennsylvania) | Why does the polarity of the earth's magnetic field switch from north to south and back again? | The process of magnetic field reversing is not completely understood although it is supposed to be related to process in the mantle. This page offers more information, especially the last topic. |
| April 23, 2008 | Sarah (age , ) | Tornadoes form from severe thunderstorms. They have a very high energy density which means that they affect a small area but are very destructive to that area. They also don't last very long which makes it hard to learn about them. More information in our website Tornadoes. | |
| April 22, 2008 | Sammy (age , ) | Tornadoes form from severe thunderstorms. They have a very high energy density which means that they affect a small area but are very destructive to that area. They also don't last very long which makes it hard to learn about them. Since they're hard to study, they're also hard to forecast. People know even less about tornadoes, which is why there are a lot of different myths that aren't true. Much more information on this topic can be found in our web page Tornadoes and the links therein. | |
| April 17, 2008 | shyanne (age 11, pennsylvania) | how is a tsunami formed? | Undersea earthquakes, which typically occur at boundaries between Earth’s tectonic plates, cause the water above to be moved up or down. Tsunami waves are formed as the displaced water, which acts under the influence of gravity, attempts to find a stable position again. More information in our webpage How Tsunamis Form. |
| April 14, 2008 | Diana (age 17, New Jersey) | What and how is a tsunami created | A tsunami is a series of waves generated in an ocean or other body of water by a disturbance such as an earthquake, landslide, volcanic eruption, or meteorite impact. The picture at the left shows how an earthquake can generate a tsunami in the overlying water. Undersea earthquakes, which typically occur at boundaries between Earth’s tectonic plates, cause the water above to be moved up or down. Tsunami waves are formed as the displaced water, which acts under the influence of gravity, attempts to find a stable position again. More information in our webpage How Tsunamis Form . |
| April 14, 2008 | Diana (age 17, New Jersey) | What and how is a tsunami created | A tsunami is a series of waves generated in an ocean or other body of water by a disturbance such as an earthquake, landslide, volcanic eruption, or meteorite impact. The picture at the left shows how an earthquake can generate a tsunami in the overlying water. Undersea earthquakes, which typically occur at boundaries between Earth’s tectonic plates, cause the water above to be moved up or down. Tsunami waves are formed as the displaced water, which acts under the influence of gravity, attempts to find a stable position again. More information in our webpage How Tsunamis Form . |
| April 10, 2008 | mike (age 68, ca, usa) | is the amount of time change in a day in a complete summer to winter cycle the same amount of change each day or varible thruout the season | Interesting question. I would say that the amount of time change is not constant during the seasons. All objects in an elliptical path follow Keppler three laws, and one of them describes how the speed of the object increases when it is near on of the focus of the orbit, in this case the sun. |
| April 9, 2008 | Christian (age 11, Virginia, USA) | What is the air density of the ionosphere? I need to know right away for a project. I've been looking everywhere for the answer. | The ionosphere consists of several layers at different heights. More information can be found in our page Ionosphere and links therein. This page shows a plot with the ionosphere densities. |
| April 7, 2008 | anjali (age 9, singapore) | if there must be a planet that has to be destroyed what would you say in order not to destroy planet earth? could you give me five reasons and in detail-thank you | Our planet is a significant depository of water and oxygen, it has abundant carbono-type life, and it is where we live!!! |
| April 3, 2008 | Beatriz (age 13, new york/ united states) | How does the color of a background affect its absorption of solar insolation? | Lighter colors will reflect more solar energy, and darker colors will absorve more energy. For example, icy surfaces reflect more energy than the ocean surface. |
| April 3, 2008 | giselle (age 9 years, ny) | why do we have seasons?how many are they? how long d they last? | The inclination of the axis of our planet is the reason for the seasons. See our page Earth's Tilt Is the Reason for the Seasons! for more information. |
| April 3, 2008 | Gaige (age 13, Illinois) | Is there any way to stop a big Earthquake? | Scientists are working hard trying to predict and mitigate the effects of earthquakes, but once the energy that produces a quake is released, it will be almost impossible to stop or divert it. |
| April 1, 2008 | niniveh (age 12, philippines) | how does greenhouse effect work? | Like in a greenhouse, where the glass ceilings don’t let heat escape, gasses in the atmosphere can trap the heat that normally would escape to the space, raising in this way the temperature in our planet. |
| April 1, 2008 | niniveh peralta (age 12, philippines) | how does greenhouse effect work? | Like in a greenhouse, where the glass ceilings don’t let heat escape, gasses in the atmosphere can trap the heat that normally would escape to the space, raising in this way the temperature in our planet. |
| April 1, 2008 | Bailey (age 12, IL) | What is the average temperature on Earth | The average range of temperature in our planet is -89oC to 57.7oC (-128oF to 136oF). |
| March 31, 2008 | Josh (age 13, Ohio) | how would you explain the nitrogen cycle? | Nitrogen is an element. It is found in living things like plants and animals. It is also an important part of non-living things like the air above and the dirt below. Atoms of nitrogen don't just stay in one place. They move slowly between living things, dead things, the air, soil and water. These movements are called the nitrogen cycle. More information in ouir web page The Nitrogen Cycle. |
| March 28, 2008 | julia (age 12, california) | why are the amounts of gases in the atmosphere measured in percentages of dry air? | The water content is not included in the calculations for the purposes of comparisons because the amount of moisture in the air is extremely variable across our planet. |
| March 28, 2008 | julia chen (age 12, california) | why are the amounts of gases in the atmosphere measured in percentages of dry air? | The water content is not included in the calculations for the purposes of comparisons because the amount of moisture in the air is extremely variable across our planet. |
| March 28, 2008 | shamari (age 10, virginia) | how do humans impact the earth negatively? | There are many human activities that affect the environment, from the consumption of fossil combustibles that emit carbon dioxide to the atmosphere, to the burning of forests in many places of the planet, we have been abusing indiscriminately our planet, and the effects are already being felt. |
| March 28, 2008 | rosette (age 12, davao, philippines) | does the position of the earth affects the climate or weather of a certain area? | The inclination of the axis of our planet is the reason for the seasons. See our page Earth's Tilt Is the Reason for the Seasons! for more information. |
| March 28, 2008 | rosette (age 12, davao, philippines) | why is it that the earth's position is tilted? | The tiltiing of our planet axis most likely happened at the beginning of the solar system formation, four and a half billion years ago, when dust and rocks were floating around and frequently crashing into each other. One or more of these impacts tilted our axis. |
| March 27, 2008 | nany (age 13, massachusetts) | how is new crust formed? | New crust is formed when molten rock or magma rises from the mantle to fill the gap between tectonic plates as they separate. |
| March 27, 2008 | tanaiya (age 9, Dallas TX) | what are rocks that have been changed by high heat or very high pressure | Metamorphic rocks are rocks that have been exposed to very hot temperature and high pressure. Some rocks only change a little, while others change a lot. When a rock is metamorphosed, its mineral crystals change. Usually, the same chemical ingredients are used to form new crystals during metamorphism. Sometimes new types of minerals grow that weren't in the rock before. |
| March 27, 2008 | Kim (age 12, Mexico City,Mexico) | What is a igneous rock?I need a definition? | Igneous rocks form when molten rock cools and becomes solid. Molten rock is called magma when it is below the Earth’s surface and lava when it is above. More information on our web page Igneous Rocks. |
| March 27, 2008 | victoria (age 13, philippines) | mohorovicic discontinuity | The Mohorovièiæ discontinuity (A.K.A the Moho) is the boundary between the Earth's crust and the mantle. |
| March 25, 2008 | Aleyda (age 16, Florida, Miami) | Why are the seasons in the Southern Hemisphere opposite to those in the Northern Hemisphere? | Because the seasons are origined because the tilt of the Earth. Our web page Earth's Tilt Is the Reason for the Seasons! discusses this topic in detail. |
| March 21, 2008 | Khadem (age 19, Ontario) | We know about the Bermuda Triangle. I have seen articles claiming that this phenomenon is due to some disturbed magnetic field of the earth. How much is this true? Can satellite pictures be used to answer the mystery of missing ships? Doesn't scientists consider Bermuda Triangle a high priority of research? | The Bermuda Triangle phenomenon, when scientifically observed, shows a very different side. This article discusses the topic. |
| March 20, 2008 | Adriana (age 11, new mexico) | what percent of each continent is covered by grasslans? | Please, visit our web page Grassland Ecosystem for information on this topic. |
| March 18, 2008 | samantha (age 15, MI) | what is winter solstice? | For the northern hemisphere this corresponds to the point where the planet's axis is tilted at its most away from the sun, and marks the shortest day and the beginning of winter. In the southern hemisphere this is the summer solstice. |
| March 17, 2008 | Christen (age 13, Utah) | The Alvin submersibile is used to explore the depths of the ocean. Just hows deep are trenches in the ocean? | The deepest trebch in the Pacific Ocean is the Mariana Trench with 10 900 to 11 000 meters. In the Atlantic Ocean it is the Milwaukee Deep with 8 605 meters. |
| March 14, 2008 | Tara (age 32, Arizona, USA) | If the moon's gravitational pull is one-sixth that of Earth's, then how does the moon pull the ocean water towards it (overcoming Earth's gravity), causing high tides? Thank you! I love this site! | Your values are right, but there a vectorial addition that explains the tides on both sides of Earth. See this article for a nice discussion on this topic. |
| March 12, 2008 | Bailee (age 11, Utah, America) | What is the Earth's magnetic pulse? | Our planet's magnetic field is not stable. Frequent undulations, lasting from seconds to minutes, are called micro-pulsations. These are frequently known as pulses. |
| March 11, 2008 | Rowanne (age 12, Philippines) | What kinds of currents Peru Current and California Current are? | The Peru current consists of cold water and runs on the northwest coast of Peru. The California Current moves south along the western coast of North America. The movement of northern waters southward makes the coastal waters cooler than coastal areas of comparable latitude on the east coast of the United States. |
| March 11, 2008 | Doug (age 11, Michigan) | What would earth's season be like if earths axis was straight up and down? | In this case, we will have very consistent seasons all year around. The difference will be now mainly latitudinal, with coldest climates for higher latitudes. |
| March 10, 2008 | Adam (age 45, ) | When is hurricane season? | The Atlantic hurricane season is officially from June 1st to November 30th. |
| March 10, 2008 | Chelsea (age 16, Canada) | Why does a storm often lessen in intensity when it hits land? | Storms are "heat engines" that require of the warm oceanic water to exist. The lack of warm water convection feeding the storm is the reason a hurricane weakens when it moves over land. |
| March 10, 2008 | Emily (age 13, Florida) | If it is winter in canada what seson is it in argentina | The seasons are caused as the Earth, tilted on its axis, travels in a loop around the Sun each year. Summer happens in the hemisphere tilted towards the Sun, and winter happens in the hemisphere tilted away from the Sun. As the Earth travels around the Sun, the hemisphere that is tilted towards or away from the Sun changes. So, when winter is arriving in the northern hemisphere, the southern hemisphere is enjoying the summer season. |
| March 5, 2008 | Laurenna (age 26, U.S.A) | During March and September the Earth receives an equal amount of energy and yet autumn is cooler than spring. Why is this? | Because the sun rays, due to the tilt of earth axis, arrive to your particular hemisphere in a lower angle during autumn, thus making the energy transfer less efficient (more of the energy is reflected back to space). |
| March 4, 2008 | abby (age 15, ohio - usa) | In December, Canada enters the winter season. What season is it in Argentina? | The seasons are caused as the Earth, tilted on its axis, travels in a loop around the Sun each year. Summer happens in the hemisphere tilted towards the Sun, and winter happens in the hemisphere tilted away from the Sun. As the Earth travels around the Sun, the hemisphere that is tilted towards or away from the Sun changes. So, when winter is arriving in the northern hemisphere, the southern hemisphere is enjoying the summer season. |
| February 28, 2008 | (age 10, California) | How does the Earth's tilt on its axis affect climate? | The tilt of our planet axis is the motive for of the seasons. For a good description of this relation, visit our web page What Causes the Seasons? and the links therein. |
| February 28, 2008 | alma (age 10, des moines iowa) | what are continental plates made up of? | The continental crust is composed of granitic rocks which are made up of relatively lightweight minerals such as quartz and feldspar. |
| February 25, 2008 | Tiana Nguyen (age 10, California, Orange County) | what color is earth? | Our planet is of a wonderful blue when seen from space. What is the Rock Cycle?. |
| February 6, 2008 | emily (canada) | WHat is the longest wetland? | The Pantanal, an area of flooded grassland and savanna covering 200 000 square kilometers during the rainy season, is considered the largest wetland. It includes parts of Brazil, Paraguay, and Bolivia and is fed by the Rio Paraguay. |
| February 5, 2008 | Chelsea (CAlifornia) | Why does the earth rotate faster than the moon? | Each planet and moon rotation is unique. A full rotation of our planet about its axis, takes 23 hours, 56 minutes, 4.2 seconds (23.9345 hours). The Moon is much slower at 655.728 hours. Many factors can affect the rotational rate of a planetary body, from how much momentum the planet gained during formation to big asteroid and comet crashes that can also change rotation. An important factor is the mass of the body, Large planets are often faster than smaller ones. |
| February 5, 2008 | Raechel (Arizona, United States) | My question is that what effect do droughts have on the economy? | A long period of drought will affect many sides of a region economy. The agricultural activity is directly hit by a drought, but also power plants, water reservoirs for human consumption, water for cattle and other animals, etc. will be affected. Forests will dry out and will be exposed to the increased danger of raging fires with high costs, including the loss of human lifes and properties. |
| February 4, 2008 | Brantley (Western Australia) | How does a magnetic field deflect solar radiation? | The plasma coming from the Sun consists of charged particles that are deflected by the geomagnetic field. Some of the highest energy particles will penetrate the magnetic field, but these are less dangerous for humans. |
| February 4, 2008 | cassandra | what is an example of nonsilicate group/sulfate and sulfites? | An example of sulfides is pyrite, also known as "fool's gold". Gypsum is an example of sulfates. Our web page Common Nonsilicate Mineral Groups shows a table with examples of each group. |
| January 31, 2008 | Lisa (California, United States of America) | I read the definition of what makes our seasons and it makes sense to me. My summer is during the summer solstice. But if I lived in Australia I would be having my winter during the summer solstice correct? Who determined the names of the solstices. Why do the names represent only half the globe? | Due to the difference on the seasons, the summer solstice of one hemisphere is the winter solstice of the other. The word solstice is derived from the Latin sol (sun) and sistere (to stand still), because at the solstices, the Sun stands still in declination; that is, its apparent movement north or south comes to a standstill. |
| January 30, 2008 | Ben (Ga, USA) | What does the eath's symbol stand for? | An extensive description of Earth's symbol can be found here. |
| January 30, 2008 | AKSHAYA (ORISSA. INDIA) | why lighting occures | During a thunderstorm, the Earth's surface has a + charge. Because opposites attract, the - charge at the bottom of the thunder cloud wants to link up with the + charge of the Earth's surface. Once the - charge at the bottom of the cloud gets large enough to overcome air resistance, a flow of - charge rushes toward the earth. This is known as a stepped leader. The + charges of the Earth are attracted to this stepped leader, so a flow of + charge moves into the air. When the stepped leader and the + charge from the earth meet, a strong electric current carries + charge up into the cloud. This electric current is known as the return stroke of lightning and is visible to the human eye. For more information visit our web page Lightning Formation. |
| January 30, 2008 | Laszlo (Hungary) | What electric charge have the Earth's solid surface at the limit with Earth's atmosphere(positive or negative)? | There is no unique value or even sign (positive or negative) for the electric charge on the earth surface. It depends upon the conditions in a particular area, for example the existence of charged clouds. |
| January 25, 2008 | kayla (tennessee) | in a summer solstice where is the sun? | Solstices occur twice a year, when the tilt of the Earth's axis is oriented directly towards or away from the Sun, causing the Sun to appear to reach its northernmost and southernmost extremes.In the northern hemisphere, the Summer Solstice corresponds to the longest day of the year (near June 22) when the Sun is farthest north. |
| January 21, 2008 | katrina (australia) | how did the earth form??? | Stars and planets form as a result of the gravitational collapse of accreting material. This material was part of the solar nebula, and transferred its rotational motion to the planets, accelerating as its radius of rotation decreases. |
| January 15, 2008 | CHERISH (GEORGIA) | what is the earth shell called | The outmost layer of the solid Earth is the crust, a thin silicate rock material. Around the planet is the atmosphere. |
| January 15, 2008 | christina (minnesota, usa) | if pollution in big cities such as New York, continue how will effect our enviroment? | Air pollution affects visibility, human health, agriculture, and ecosystems. As cities around the world grow bigger than ever before, scientists are discovering that urban air pollution is powerful enough to affect Earth's weather and climate. In a recent (very importante) study, scientists from all over went to Mexico City for the MILAGRO (Megacity Initiative: Local and Global Research Observations) campaign. Please, visit our web page Introduction to MILAGRO for more details. |
| January 12, 2008 | rylee (Pa, USA) | What igneous rock turns into limestone and then marble in the rock cycle? | Please, find an extensive answer to your question The Desert Ecosystem for more information. |
| January 12, 2008 | marissa (maryland,usa) | where are the tropical rainforest located? | This map shows the area of tropical rainforest. |
| January 10, 2008 | abeer (ontario/canada) | Are metamorphic rocks only ones that get melted back into magma? Explain | No, all types of rocks can be melted by magma. For example, sedimentary rock can be re-melted back into the magma to become igneous rock. |
| January 10, 2008 | kevin | how man volcanoes does earth have | For volcanologists, "active" means does the volcano have the possibility of erupting again.The Smithsonian Institution uses this last definition in their web page Global Volcanism Program, and lists about 1300 active volcanoes, but these figures do not include the large number of eruptions (and undescribed volcanoes) on the deep sea floor. |
| January 8, 2008 | Noraini (Philippines) | how does island arcs form? | Island arcs are a arc-shaped chain of volcanic islands produced where an oceanic plate is sinking (subducting) beneath another. |
| January 8, 2008 | Autumn (charoltte) | what are grasslands | Grassland are grass-dominated areas where few or no trees grow. Includes prairies and savannas. |
| January 8, 2008 | Meghan (Florida) | How do clouds form over mountains? | Clouds form as an air parcel rises and cools, and the water vapour content condenses when it reaches the dew point. Lenticular clouds in particular are caused by a wave wind pattern created by the mountains. They look like discs or flying saucers that form near mountains. |
| January 7, 2008 | isabelle (Autralia) | is there fresh water or salted water in Antartica | Mainly fresh water. Glaciers and ice caps store about 75% of the world's freshwater. |
| January 7, 2008 | manasi (Maharashtra/ India) | I wantto know the temperature of the magma at the time when it spills out ? THANK YOU | When the magma spills out is called lava. Lava temperatures during an eruption can reach up to about 1170 degrees centigrade. |
| January 4, 2008 | NETAIYAH (MISSISSIPPI) | WHAT % OF EARTH IS FRESH WATERTRAPPED IN FROZEN ICECAPS AND GLACIERS? | Glaciers and ice caps store about 75% of the world's freshwater. |
| January 2, 2008 | emily (georgia/north america) | what is the most dangerous volcano | The last three volcanic eruptions to cause major loss of life were Krakatoa, Indonesia, where 32,000 were killed in 1883; Mt. Pelee, Martinique, where 29,000 were killed in 1902; and Nevada del Ruiz, Colombia, where 23,000 were killed in 1985. Extracted from THE MOST DANGEROUS VOLCANO IN THE WORLD by Wiliam Menke. |
| January 2, 2008 | Eric (Michigan) | What is the name of a famous spatter cone volcano? Would it be the same as a cinder cone volcano? | Spatter are very fluid fragments of molten lava ejected from a vent that flatten and congeal on the ground. An example is Kilauea Volcano. |
| January 2, 2008 | Logan (victoria,australia) | hey, my question is: If the moon stopped spining on its axis half the earth would be night all the time and half the earth would be day all the time how would this effect humanity? thank you. |
I don't believe that the stopping of the moon rotation will affect the days and nights on Earth. Days and nights are due to the rotation of Earth around its axis. |
| January 1, 2008 | Forest (Colorado) | What are "Goldilocks Conditions"? | Our web page The Goldilocks Theory describes in details this topic. Essentially this theory states that the Earth seems to be just right for conditions favorable to life. The reasons have to do with the fact that the Earth seems to be the perfect distance from the sun for abundant liquid water. |
| January 1, 2008 | Shaanika (Namibia) | what is the sole generator of magnetic field? | A magnetic field can be generated from many sources and methods. But if your are asking about earth's mgnetic field, then it is generated by a so-called "dynamo". This page has a nice description of the process. |
| December 27, 2007 | BELINDA (AL;DECATUR) | IS THER ANY EVIDENCE ON THE GLOBE THAT THE EARTH'S SURFACE AND ATMSHERE ARE ACTIVE ?IF SO DESCRIBE IT. | Just one example for each one: earthquakes (surface) and hurricanes (atmosphere). |
| December 26, 2007 | Kathy (Florida USA) | Could the magnetic field have changed when the planets were placed in the solar system, which would have caused a great change in the magnetic pull, thus giving us a fingerprint for creation and showing which planets were placed in our solar system by a certain order, based on the pull (time difference)? | The planets with a recordable magnetic field are quite different among them. The magnetic fields have different characteristics, different interactions with the solar wind, different orientation, etc. It would be hard to compare them to obtain their time life. |
| December 26, 2007 | Teresa (California San Francisco) | In the future, will there be no North or South Pole because of global warming? | South Pole has solid ground under the ice, but this is not the case for the North Pole. Now, we don't kow for certain if the whole polar ice sheet will be melted. |
| December 21, 2007 | Keila (PA) | Why is the equator a fixed position on the globe while the Prime Meridian could be placed anywhere on the globe? | The North and South hemispheres, divided by the equator, have very distinct seasons along the year, while nothing similar happens to East and West hemisphere, as delimited by the Prime Meridian. |
| December 19, 2007 | laura (australia NSW) | diagrams of tsunamis caused by earthquakes | This page has a good animated diagram. |
| December 17, 2007 | Mili (Gujarat,India.) | What might be the consequences if Earth's core cools down like the crust? | One of the immediate consequences would be the weakening of the magnetic field that surrounds and protects our planet. |
| December 10, 2007 | The distances to the magnetosphere boundaries are usually expressed from the center of our planet. | ||
| November 7, 2007 | tai (new zealand) | how many feet is mount vesuvius ? | The elevation of Mount Vesuvius is 1,281 M (4,203 FT). |
| October 16, 2007 | Ronnel (Philippines) | What is nitrogen cycle? | Nitrogen is an element. It is found in living things like plants and animals. It is also an important part of non-living things like the air above and the dirt below. Atoms of nitrogen don't just stay in one place. They move slowly between living things, dead things, the air, soil and water. These movements are called the nitrogen cycle. More information in our web page Nitrogen Cycle. |
| October 16, 2007 | Ronnel (Philippines) | What are the segnificance of carbon cycle? | Next is only a way to look at this issue, for more information, visit our web page Carbon Cycle. Carbon moves through our planet over longer time scales. For example, over millions of years weathering of rocks on land may add carbon to surface water which eventually runs off to the ocean. Chemical weathering of silicate minerals, in particular, can have an effect on the amount of carbon dioxide in the atmosphere. Additionally, over long time scales, carbon is removed from seawater when the shells and bones of marine animals and plankton collect on the sea floor. These shells and bones are made of limestone, which contains carbon. When they are deposited on the sea floor, carbon is stored from the rest of the carbon cycle for some amount of time. The amount of limestone deposited in the ocean depends somewhat on the amount of warm, tropical, shallow oceans on the planet because this is where prolific limestone-producing organisms such as corals live. The carbon can be released back to the atmosphere if the limestone melts or is metamorphosed in a subduction zone. |
| October 16, 2007 | Matthew (California,united states) | if the mesosphere is the coldest then how can meteors get burned? | Meteors get burned due to the friction with the air, and not because of the temperature. |
| October 16, 2007 | gayle (philippines) | what are the layers of water | Our web page The deep Waters of the Ocean offers an extensive information on this topic. |
| September 19, 2007 | Erin (Iowa, USA) | What would happen in the sun would shine only one day per month? | We will only get 12 days of sunshine. It is safe to expect a catastrophic cooling of the planet. |
| September 19, 2007 | Erin (Iowa, USA) | What would happen in the sun would shine only one day per month? | We will only get 12 days of sunshine. It is safe to expect a catastrophic cooling of the planet. |
| September 19, 2007 | Cathy (Akron, OH) | Why don't we have any physical sensation of movement as the earth spins on its axis and orbits the sun? | From a Newtonian point of view we are at rest with respect to the planet. Due to the lack of a close enough point of reference, we can't see or feel the motion. |
| September 12, 2007 | Roxy (Florida) | What is the mass of one cubic meter of continental and/or oc eanic crust? | The density of continental crust is about 2.7 g/cm³ (grams per cubic centimeter) or 2 700 kg/m³ (kilogram per cubic meter). The average density of the oceanic crust is 3 g/cm³ = 3 000 kg/m³. |
| September 12, 2007 | mae (philippines) | what is doforestation? | Deforestation is the permanent destruction of indigenous forests and woodlands. Deforestation has resulted in the reduction of indigenous forests to four-fifths of their pre-agricultural area. |
| September 12, 2007 | rhamae (Philippines) | what is rock cycle | All rock (except for meteorites!) that is on Earth today is made of the same stuff as the rocks that dinosaurs and other ancient life forms walked, crawled or swam over. While the stuff that rocks are made from stays the same, the rocks do not. Over millions of years, rocks are recycled into other rocks. Moving tectonic plates help to destroy and form many types of rocks. Please, visit our webpage Rock and the Rock Cycle for more information. |
| September 12, 2007 | Although the tripulation of Apollo 16 took pictures and performed research tasks that included use of an ultraviolet camera/spectrograph - the first astronomical and Earth observations taken from the Moon's surface in 1972, currently there are not instruments on the Moon. However, more recently, a NASA Advisory Council subcommittee has taken on the task to consider the use of Moon-based instruments to study the Earth. | ||
| September 11, 2007 | alexandra (america/florida) | What physical factors and positions, or movements, of the earth cause different amounts of energy to strike the surface of the earth? | The different amounts of solar energy that reach different areas of our planet is mainly due to the tilt of the Earth's axis. In other words, the tilt of Earth's rotational axis and the Earth's orbit work together to create the seasons. Please, visit our webpage Earth's Seasons for more information. |
| September 4, 2007 | guadalupe (nevada) | Is it true tha if people dont stop using hair spray the amospher will pop and we will die burning | The CFCs (Chloro-Fluoro-Carbons) were used in air conditioners, spray cans (including hair sprays) and foam materials. Their use has been regularly prohibited by the Montreal Protocol, because of effects on the ozone layer and because they also are a powerful greenhouse gas. |
| August 21, 2007 | David (ENGLAND) | Is the earths gravitational pull (escape velocity) less at the equator than at the poles - due to its rotation causing a centrifugal force. The centrifugal force would be greater at the equator compared to the poles ? |
Yes, the centrifugal force is greater at the equator and hence the gravitational force is lower. |
| August 17, 2007 | kenneth (philippines) | what is a water cycle? please help me because i need to explain this to my teacher. | The Earth's water is always in circulation. It has been recycled for the last 3 billion years. This process is called the water cycle. The cycle starts when the sun's heat evaporates water from the oceans into the atmosphere to form clouds. When the conditions are just right, the clouds release water as rain or snow. Most of the rain falls in the oceans, but the rest falls onto land. Rivers and streams collect water from the ground and return it to the ocean so the whole cycle can start all over again. The water cycle never ends because the salty ocean water constantly supplies fresh water to the continents. More information in our web page Water Cycle and the links therein. |
| August 17, 2007 | kenneth (philippines) | what is a water cycle? please help me because i need to explain this to my teacher. | The Earth's water is always in circulation. It has been recycled for the last 3 billion years. This process is called the water cycle. The cycle starts when the sun's heat evaporates water from the oceans into the atmosphere to form clouds. When the conditions are just right, the clouds release water as rain or snow. Most of the rain falls in the oceans, but the rest falls onto land. Rivers and streams collect water from the ground and return it to the ocean so the whole cycle can start all over again. The water cycle never ends because the salty ocean water constantly supplies fresh water to the continents. More information in our web page Water Cycle and the links therein. |
| August 17, 2007 | vibhav (u.p./ India) | why is the axis of Earth tilted? | All the planets have axial tilts. The predominant theory is that this occured due to collisions in their formative phase. |
| August 17, 2007 | jai (india) | why we do not rotate with earth? | We do!!!! Because we are fixed to the surface we don't notice this rotation, but there are several ways to prove it, including the motion of the sun and stars in the sky. |
| July 23, 2007 | nori (united states) | what is magnetic earth | I am not sure what you meant by "magnetic earth". Our planet, and many others, generates a magnetic field. This field is roughly similar to a bar dipole magnetic field. The solar wind interacts with this field to produce, under the right conditions, the beautiful auroras. |
| July 21, 2007 | Phil (California) | What affect would the presence of two or three moons have on the earth? | For starters, a way more complicated tide system (due to a more complex gravitational pull), more partial and total Sun and moon eclipses, and a more beautiful sky! |
| July 21, 2007 | Phil (California) | What affect would the presence of two or three moons have on the earth? | For starters, a way more complicated tide system! |
| July 21, 2007 | Faith (Florida, USA) | Where is the closest lithospheric plate to us here in Florida? What type of boundary is it and what types of processes occur there? | Florida is on the North American plate, near the Caribbean plate. This two plates have a transform boundary. This type of boundary occurs when tectonic plates slide and grind against each other along a transform fault. |
| July 21, 2007 | elizabeth (Philippines) | How does the air affects the movement of the earth? | Our web page Can Earth’s Spin Be Changed by Wind? answer your question in detail. |
| July 20, 2007 | Glen (Auckland, New Zealand) | When half the world is facing away from the Sun, why does it not completely freeze? | Because all bodies have a property known as "heat capacity" (ability of a body to store heat as it changes in temperature). The heat stored is slowly release during the night, keeping a more or less uniform temperature in our planet. |
| July 20, 2007 | lionel (alalbam/usa) | in what countries does the sun shine 24 hours on the longest day of the year? | Sunrise and sunset at the poles take a long time. At the poles, the Sun does not go higher and lower in the sky each 24-hour day, but goes very slowly up in the spring or down in the summer. During a 24-hour period, the Sun goes all the way around the sky at almost the same height. More information at Astronomy Answers. |
| July 20, 2007 | Elizabeth (New Zealand) | How far is the sun from earth? | Due to the excentricity of the orbit of our planet, the distance to the Sun change along the year. The Minimum Distance from Sun is 146 million km (91 million miles), and the Maximum Distance from Sun is 152 million km (94.5 million miles). |
| July 20, 2007 | reg (canada) | what are the longest and shortess days of the year in ontario canada | In the Northern Hemisphere the summer solstice (June 21 this year) is the longest day in the year, and the winter solstice (December 22 this year) is the shortest day (and longest night) of the year. |
| July 19, 2007 | Brahmani (Hyderabad) | WHY WE SAY EARTH AS PLANET? | There are many definitions of planet, all of them with certain degree of ambiguity, one of them is: A spherical object orbiting a star that is not a brown dwarf but is bigger than an asteroid. Our plane fulfills this definition. |
| July 18, 2007 | ritu (mumbai,india) | will earth be over because of global warming, can nothing be done what we all can afford to do? | I believe humanity is right now at a crucial point of its history. Many efforts are already in place, and most importantly, normal people, like you and me, are realizing the seriousness of the situation. Now it is in hands of politicians and corporations to do their part, and we should let them know so. |
| July 18, 2007 | shana (south Australia) | does the distance from the sun infulence the climate and temperture of a coutry ver much? | Not really, the distance to the Sun is roughly the same for all the planets. An important factor for climate and temperature is the latitude of the country. At higher latitudes (closer to the poles) the angle of incidence of the Sun rays is lower, and because that the mean temperature of the region will be lower. |
| July 18, 2007 | bhoomika (india) | why are volcanoes formed? | Volcanoes form when hot material from below rises and leaks into the crust. Our web page Volcano formation offers more information. |
| July 18, 2007 | bhoomika (india) | why are volcanoes formed? | Volcanoes form when hot material from below rises and leaks into the crust. Our web page Volcano formation offers more information. |
| July 18, 2007 | Richard (Wisconsin USA) | Is it possible that the oceans floor was once land and it flooded somehow and new land has formed from volcanos?? | This activity from the U.S. GEOLOGICAL SURVEY describes in a very clear way the processes related with sea-floor spreading. |
| July 18, 2007 | MANIK (INDIA) | HOW LONG WILL EARTH LIVE. | The answer to your question is still open. What we know is that a star with a mass similar to that of our Sun and in the last phase of its life is a red giant. Hydrogen fusion reactions have become less efficient in the core region, and the fusion reactions now occur in a shell surrounding the core. The outer layers then cool to about 3000 K and becomes a red star of a huge size, reaching the orbits of all the interior planets. |
| July 17, 2007 | Danaca (America) | How long do you think it will be until Global Warming comes to affect and kills us all, if ever? | Our planet is already suffering the effects of the global warming. We have several page in our website that are related to this issue: -- Melting Arctic Sea Ice and the Global Ocean Conveyor -- The Cryosphere and Global Climate Change -- Climate and Global Change News -- Warming of the Polar Regions -- Warming of the Polar Regions The links therein will offer additional information. |
| July 17, 2007 | Monae (New Jersey) | How do a tornado form? | A tornado begins in a severe thunderstorm called a supercell. A supercell can last longer than a regular thunderstorm. The same property that keeps the storm going also produces most tornadoes. The wind coming into the storm starts to swirl and forms a funnel. The air in the funnel spins faster and faster and creates a very low pressure area which sucks more air (and possibly objects) into it. More information in our web page How a Tornado Forms. |
| July 17, 2007 | Cherika (Washington/ USA) | What is the significance of the SAL (Sahara air layer) to the development of a hurricane? | This NOAA press release should answer your question. |
| July 17, 2007 | Emily (Lake Forest, Ca) | I would like to know the fossils are trapped in the rocks, and how are the rocks formed three ways? | The rocks are classified in three groups: Igneous rocks: formed from the cooling and solidification of magma. Sedimentary rocks: formed at the surface of the Earth from the accumulation of sediments (fragments of rocks, minerals, or animal or plant material) Metamorphic rocks: formed within the Earth's crust when other rocks are subjected to pressures or heat so intense that they are completely changed. For more information visit our page Rocks and the Rock Cycle. |
| July 17, 2007 | Emily (Lake Forest, Ca) | I would like to know the fossils are trapped in the rocks, and how are the rocks formed three ways? | The rocks are classified in three groups: Igneous rocks: formed from the cooling and solidification of magma. Sedimentary rocks: formed at the surface of the Earth from the accumulation of sediments (fragments of rocks, minerals, or animal or plant material) Metamorphic rocks: formed within the Earth's crust when other rocks are subjected to pressures or heat so intense that they are completely changed. For more information visit our page Rock and the Rock Cycle. |
| July 17, 2007 | Sanjana (New Delhi,India) | please can you tell me the types of forest ecosystem( is it right to put TAIGA under forest ecosystem)? | Yes, taiga is a forest ecosystem. |
| July 17, 2007 | tyler (california/us) | What kind of a eruption does a cinder cone volcano have? | As the gas-charged lava is blown violently into the air, it breaks into small fragments that solidify and fall as cinders around the vent to form a circular or oval cone. |
| July 17, 2007 | Daniel (maryland) | what causes the sun to appear red during sunrises | The Sun looks red during a sunset because of Earth's Atmosphere. When the Sun goes down, we see it through gases and dust that are in the sky. The color it appears to be depends on what is in the air. If you see red, it is because all the other colors are being absorbed by the particles, but the color red is being reflected. |
| July 17, 2007 | Daniel (maryland) | what causes the sun to appear red during sunrises | The Sun looks red during a sunset because of Earth's Atmosphere. When the Sun goes down, we see it through gases and dust that are in the sky. The color it appears to be depends on what is in the air. If you see red, it is because all the other colors are being absorbed by the particles, but the color red is being reflected. |
| July 17, 2007 | Bea (Munich) | I have to do a report on Global warming, and I was wondering where to find some information. Do you have any links, or some facts about Global Warming? What is Global warming generally? | We have several page in our website that are related to this issue: -- Melting Arctic Sea Ice and the Global Ocean Conveyor -- The Cryosphere and Global Climate Change -- Climate and Global Change News -- Warming of the Polar Regions -- Warming of the Polar Regions The links therein will offer additional information. |
| July 11, 2007 | Ana (California) | What causes the difference in the Northern and Southern hemispere wind? | There are different seasons to take in account. |
| July 10, 2007 | Greggory (AR, USA) | Are there "holes" at the Earth's poles? I thought the idea was crazy until I was unable to get clear, detailed polar photos. Is there something there our government and the scientific community is hiding? | As a part of that scientific community I can assure you that there is nothing to hide. The poles are critical elements of our planet climate, and right now they are the main objective of a global effort: the International Polar Year (IPY). Our webpage International Polar Year - and IPY's of the Past also offers information on this topic. |
| July 10, 2007 | rachel (asia) | how are fold mountain form? | Fold mountains are formed when two plates move together. The movement of the two plates forces sedimentary rocks upwards into a series of folds. As a curiosity, visit this webpage for a very different type of "fold mountain". |
| July 9, 2007 | Kenneth (Florida, USA) | How is called the movement of water from air to Earth and back again? (2 words) | What you are describing is part of the Water Cycle. |
| July 9, 2007 | Vijay | That would mean that our planet is not moving any more around the Sun, and all things related with these motions will stop. For example, we wouln't have days and nights or seasons! | |
| July 9, 2007 | j (rosevill) | what is a autumnal equinox and a spring quinox | The spring and autumn equinoxes occur around March and September 21. These are special points in the Earth's orbit when the Sun appears directly above the Earth's equator. Day and night are the same length, about 12 hours. For more information, visit our webpage The Spring and Autumn Equinoxes. |
| July 6, 2007 | Kaitlyn (Ohio) | Can you explain why and how the moon's gravity can cause the oceanic tides? | Due to the mutual gravitational atraction between the Earth and its moon, there are forces acting over both. In the case of our planet, the only element that can be moved is liquid, and the bigger bodies of water show the effects of this atraction in the form of tides. |
| July 5, 2007 | Michelle (Denver Colorado) | Where doesmost fo the rain/precipition fall in Colorado? | In general, most of the precipitation fall on the mountains. For a more detailed answer to your question go to this webpage of the Colorado State University. This map is particularly informative. |
| July 5, 2007 | Michelle (Denver Colorado) | Where doesmost fo the rain/precipition fall in Colorado? | In general, most of the precipitation fall on the mountain. For a more detailed answer to your question go to this webpage of the Colorado State University. This map is particularly informative. |
| July 5, 2007 | Michelle (Denver Colorado) | Where doesmost fo the rain/precipition fall in Colorado? | The answer to your question can be found at this webpage of the Colorado State University. This map is particularly informative. |
| July 5, 2007 | Michelle (Denver Colorado) | Where doesmost fo the rain/precipition fall in Colorado? | The answer to your question can be found at this webpage of the Colorado State University. This map is patircularly informative. |
| July 3, 2007 | Bobby (Florida United States) | Where is Calcite found? | Calcite is typically found in the sedimentary rock called limestone. Calcite is also in marble, a metamorphic rock, which forms when limestone is put under strong heat and pressure. More information in our webpage Calcite. |
| July 3, 2007 | Nikki (Ohio USA) | About how much of the world is covered in grasslands/savannas | Grasslands/savannas are one of the Earth's major ecosystems. The estimates of the amount of the Earth's land surface covered by them vary considerably, but almost all scientists consider a minimum of 15%. |
| June 28, 2007 | amanda (kansas) | what is a convergent boundry | In plate tectonics, a convergent boundary is an actively deforming region where two (or more) tectonic plates or fragments of lithosphere move towards one another. |
| June 28, 2007 | Charis (Arizona, U.S.) | How big is Earth i miles? | The diameter of our planet is 12 753 km = 7,926 miles. |
| May 30, 2007 | chelsea (ny) | what is the eye of a hurricane | The eye is the calmest part of a hurricane. Surrounding the eye is the eye wall, which is the most violent part of a hurricane. The eye wall is almost a complete ring of thunderstorms and contains the strongest winds in the hurricane. More information in our web page Eyes and Eye Walls of the Hurricane. |
| May 21, 2007 | Megz (Wales) | What is the form of weathering effect called that could split open a piece of rock when water freezes into ice? | There are two main classifications of weathering: Mechanical weathering (involves the breakdown of rocks and soils through direct contact with atmospheric conditions such as heat, water, ice and pressure), and Chemical weathering (involves the direct effect of atmospheric chemicals), in the breakdown of rocks, soils and minerals. |
| May 21, 2007 | Tyasia (florida) | how was earth formed and how and when was earth discovered | Scientists believe that the solar system was formed when a cloud of gas and dust in space was disturbed, maybe by the explosion of a nearby star (called a supernova). This explosion made waves in space which squeezed the cloud of gas and dust. Squeezing made the cloud start to collapse, as gravity pulled the gas and dust together, forming a solar nebula. Just like a dancer that spins faster as she pulls in her arms, the cloud began to spin as it collapsed. Eventually, the cloud grew hotter and denser in the center, with a disk of gas and dust surrounding it that was hot in the center but cool at the edges. The planets and moons were formed from this solar nebula. For a description of the formation of our system, please visit our web page Solar System Formation. |
| May 21, 2007 | Liam | how does thunderstorms form | In a calm sky, the positive (+) and negative (-) charges are evenly distributed and so the calm sky has a neutral charge. Inside a thunderstorm, electric charge is divided, with + charge at the top and - charge at the bottom. Under these conditions, the ground has + charge, and because opposite charges are attracted, .the - charge at the bottom of the thunderstorm cloud wants to meet the + charge of the ground. The jump of the charges happens so fast that all we can see is a line of light. This is called lightning. More information on this topic can be found in our page Lightning Formation. |
| May 11, 2007 | Valentina (Bogota, Colombia) | Does the pressure of the plates affect the height of the tsunami? | The magnitude of the disturbance causing the tsunami is the primary factor influencing the size and strength of the waves. Tsunamis are most often triggered by earthquakes, but they can also be produced by landslides, volcanic eruptions, explosions and the impact of meteorites or asteroids. |
| May 10, 2007 | Maricela (CA) | Is MountSt.Helens a Composite Volcano | Mount St. Helens is a composite cone (has erupted both lava flows and ash flows). |
| May 7, 2007 | may (teaxes) | a metamorphic rock that has visble layers or bands. | Foliated metamorphic rocks have visible layers or bands. |
| May 7, 2007 | samantha (fl/usa) | how many moons dose the earth have. | Just one, our beautiful Moon! |
| May 5, 2007 | Yashna (Chandigarh) | What are meteorites? | A meteorite is a relatively small extra-terrestrial body that reaches the Earth's surface. While in space these bodies are called meteoroids and are called meteors after entering Earth's atmosphere, but before reaching the surface. These are "small" asteroids, approximately boulder-sized or less. Upon entering the atmosphere, air drag and friction cause the body to heat up and emit light, thus forming a fireball or shooting star. More information on our web page Meteors. Definition from Wiki/Meteorites. |
| May 5, 2007 | Sarah (New York, United States of America) | Will there ever be a super tsunami? | A super- or mega-tsunami could happen under specific conditions. The collapse of the volcano Cumbre Vieja in the island of La Palma, in the Canary Islands in the Atlantic Ocean, has been mentioned as one of the possible causes for a mega-tsunami. The impact of a meteorite os a considerable size could also create a mega-tsunami. |
| May 5, 2007 | Antonella (Costa Rica) | What percentage of the earth is covered by ice? | Almost 10 percent of the world's land mass is currently covered with glaciers, mostly in places like Greenland and Antarctica. |
| May 5, 2007 | Antonella (Costa Rica) | What area (m2 or km2) does the current area covered by ice in north pole and the south pole have? | The sea ice extent in the Nothern Hemisphere in March 2006 covered an area of 14.5 million square kilometers, in September 2006 covered an area of 5.9 million square kilometers. (seasonal minimum and maximum). The corresponding values in the Southern Hemisphere were 2.7 million square kilometers for February 206, and 19.3 million square kilometers during September 2006. |
| April 19, 2007 | Karleena | Our web page The Earth's Atmosphere , and the links therein, provide a significant amount of information about our planet atmosphere. | |
| April 19, 2007 | Casi (florida us) | If i weight 75 pounds on earth. What would I weigh on mars? | Our planet gravity (at sea level) is 9.8 m/s2. Mars surface gravity is 3.7 m/s2 (0.37 x Earth's). So, your weight there will be 75 lbs x 0.37 = 27.8 lbs. |
| April 19, 2007 | stephanie (Texas United States) | when will the earth end and what will happened when it does? | In about 5 billion years, the hydrogen in the center of the Sun will start to run out, the helium will get squeezed, and this will speed up the hydrogen burning. Our star will slowly puff into a red giant and will eventually eat all of the inner planets, even the Earth. |
| April 19, 2007 | Christian (Western Australia) | If the moon rotates so that the near side always faces the earth, and the orbits of the moon and earth are such that a full moon appears when the sun and moon are on opposite sides the earth and a new moon appears when the moon sits between the sun and the earth, how can there be a dark side of the moon. Ie With a full moon, the sun shines on the near side and reflects directly back to earth. With a new moon, the near side is in shaddow and therefore the far side must be illumunated. If the near side is a constant face to us, how can there be a dark side if that face is in sunlight during a full moon and in darkness during a new moon? | You are absolutely right, there is not a dark side of the Moon!!! Only a side that we can't see from Earth. |
| April 19, 2007 | Jeni (Ontario Canada) | Is it possible for the earths rotation to be altered? I have read that some "wobbles" in our rotation have been linked to earthquakes. (reported in 2003) | NASA scientists using data from the Indonesian earthquake calculated it affected Earth's rotation, decreased the length of day, slightly changed the planet's shape, and shifted the North Pole by centimeters. The earthquake that created the huge tsunami also changed the Earth's rotation. Read the full article here. |
| April 19, 2007 | carolina (united states) | Could the early atmosphere support life as we know it? | As the pre-Cambrian era came to a close, and oxygen levels in the early atmosphere began to approach 1% of what they are today, more and more advanced life forms began to appear. Rather than a single cell, life forms now were multi-cellular. |
| April 19, 2007 | Jo (Kansas) | when the poles reverse, does the magnetosphere disappear? If so, does the solar wind reach the earth's surface? | During the reversal the magnetosphere would become very unstable, week, and complex, but it wouldn't disappear. Under these conditions it is very likely that the solar protons will easily reach the atmosphere, but there won't be any significant change on the ground level because the continuous protection of our atmosphere. |
| April 7, 2007 | Kayla (West Liberty) | Why is the crust important, or what is its there for? | While the crust is very thin in comparison to the other three layers (only about 8 km, 3-5 miles thick under the oceans and about 32 km, 25 miles thick under the continents, it is the layer where we lived! |
| April 7, 2007 | Storm (Australia) | Why does the moon exist? | There are three theories about how the moon came to be in place: - that the moon came out of the crust of the Earth - that the moon was captured by the Earth - that the Earth and moon formed together out of the primordial nebula. |
| April 4, 2007 | jada (georgia) | Where can you find the Auroras?(on earth) | The auroras are commonly seen around the polar regions. At times, under very disturbed geomagnetic conditions, these beautifull lights can be seen at lower latitudes. |
| April 4, 2007 | jada (georgia) | What are the Auroras? | The auroras are a luminous atmospheric phenomenon that generally appear as bright colorful bands of light. They are commonly seen around the polar regions. At times, under very disturbed geomagnetic conditions, these beautifull lights can be seen at lower latitudes. Our page The Aurora offers more information, links, and pictures of auroras. |
| April 4, 2007 | jada (georgia) | What are the Auroras? | The auroras are commonly seen around the polar regions. At times, under really disturbed geomagnetic conditions, these beautifull lights can be seen at lower latitudes. |
| March 31, 2007 | sally (canada,nova scotia) | is it true that if the planets move, not orbit, they wo uld explode? | A planet, to be considered as such, "has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape" (extracted from the definition of planet by the International Astronomical Union). This means that planets' shape are obtained from their own mass, not from external factors. Of course, if a planet is moving outside the gravitational field of a star, it is not a planet, because it fails to fullfill the first condition of the definition of planets: "is in orbit around the Sun". |
| March 31, 2007 | ryan (idaho) | How are the Earth and Moon similar? | The interior of the Moon is very similar to the interior of our planet: an iron rich core, a plastic asthenosphere, a thick mantle, and finally a thin crust. |
| March 27, 2007 | Rogina (Anderson,Texas) | What is the diameter of Earth? | Earth's diameter is 12 753 km (7,926 miles). For more interesting planetary facts, visit our web page Earth Statistics. |
| March 27, 2007 | Rogina (Anderson,Texas) | What is the diameter of Earth? | Earth's diameter is 12,753 km (7,926 miles). For more interesting planetary facts, visit our web page Earth Statistics. |
| March 26, 2007 | aiden (IN, USA) | Why does the North end of a compass always point North? I thought that like charges repel. | Exactly! The same rule of "opposites attract" is at work here. The colored part of the compass needle that will point to the North is the South pole of the magnetized needle. To be accurate, the Earth magnetic poles are not exactly at the same spots as the geographic poles, the magnetic north pole is around 1 400 miles away from the geographic north pole. |
| March 23, 2007 | RADHIKA (DELHI/INDIA) | What kind of life existed exactly 3000 years ago/ | The life on our planet has not suffered drastic changes in the last 3 000 years. Humans were already roaming, and most of the animals and plants were basically the same. To have a better idea of the changes suffered by our planet, visit our web page Geologic Time. |
| March 23, 2007 | Belen (Florida/United States of America) | Where does the energy from Earth's core come from? | Our planet's core is hot because of radioactive heating. The core is full of radioactive elements producing heat as they decay. |
| March 23, 2007 | Jessica (ny) | how do rocks change spots within the rock cycle? | The rock cycle transforms rocks from one type to other, and, with these transformations, moves then around. More information can be found in our web page Rock Cycle and the links therein. |
| March 20, 2007 | Beck (U.K.) | How deep is the Earth from surface to centre? | The radius of the Earth is measured from the center of the Earth to the sea level at a given point. This value is at the equator 6 378.135 km. |
| March 5, 2007 | When moving to the west, we will see a later sunrise, and a same time amount of a later sunset, so the length of the day stays the same! However, different seasons do change the length of the day (equally for all longitudes) | ||
| February 24, 2007 | denise (california/united states) | how do metamorphic rocks form? | Metamorphic rocks are formed within the Earth's crust when other rocks are subjected to pressures or heat so intense that they are completely changed. |
| February 24, 2007 | meg (W.A) | at what angleis the earth tilied. | The tilt of our planet's axis is 23 degrees 27minutes. More interesting facts are at our web page Earth Statistics. |
| February 22, 2007 | omar (egypt) | what is in the space junk ? | Whether on Earth or in Space, human activity creates waste. Like the Earth's environment, the space environment is getting more and more cluttered. There are currently millions of man-made ruins that make up "space junk". Unfortunately, the past 30 years of space exploration have generated a lot of junk that poses a significant threat to spacecraft now in orbit. Orbital debris includes things such as hatches blown off space modules, paint fragments from the space shuttle, or satellites that are no longer in use. For more information, visit our page Junk in Space!. |
| February 13, 2007 | saar (uttar pradesh) | why r the earth a planet? what is the area of earth? | Earth is a planet because it fulfills the definition of planet by the International Astronomical Union (IAU): A planet is a celestial body that - is in orbit around the Sun, - has sufficient mass for its self-gravity to overcome rigid body forces, and - has cleared the neighborhood around its orbit. |
| February 12, 2007 | Keisha (Tenneessee) | What is the streak of feldspar | Feldspar is the most common mineral in the Earth’s crust, so you are very likely to find traces of it (streaks) in the rocks you collect! Please, visit our web page Feldspar for more information. |
| February 12, 2007 | Kayla (Missouri) | how does the moon orbit the earth? | There are three theories about how the moon came to be in place: - that the moon came out of the crust of the Earth - that the moon was captured by the Earth - that the Earth and moon formed together out of the primordial nebula In all cases, the Moon is trapped by our planet gravitatory field. |
| February 5, 2007 | ayaka (honolulu, hawaii) | how big in killometers is earth? | Our planet has a diameter of 12 753 km, and a mass = 5.98x10^24 kilograms. More of Earth's planetary facts at Earth Statistics. |
| January 29, 2007 | natalie (uk) | at what lattitude are day and night the same lengths all year round? | If you live in a place that is far from the equator, you may have noticed that during winter there are fewer hours of sunlight than during summer. This is because of the tilt of Earth’s axis. Earth's tilt is the reason for the seasons. The closer you are to one of Earth’s poles, the less sunlight there is during winter days. At the Arctic and Antarctic Circles there is one full day when the Sun does not set and one day when it does not rise. The Sun does not set on the summer solstice (June 21 in the north and December 21 in the south) and does not rise on the winter solstice (December 21 for the north and June 21 for the south). In the weeks prior to the winter solstice, the number of hours with sunlight become fewer and fewer until on the winter solstice when the Sun does not rise at all for a day. After the winter solstice the amount of daylight increases each day until the summer solstice when the Sun does not set at all for one day. For more information, visit our web page Geography of Earth's Polar Regions. |
| January 29, 2007 | Bob (Massachusetts / USA) | What is the Circumference of the earth ? | The circumference of the Earth is 24,901.55 miles (40 075.16 km) at the equator. If we were measuring around the poles, the circumference would be a bit shorter. Much more information about our planet can be found at our web site Earth Numbers and Earth. |
| January 25, 2007 | Jordan (Florida/ united states) | How is the ocean floor mapped? | There are several methods to map the sea floor. For example, the U.S. Geological Survey describes a recent sea floor mapping: "The sea floor of the Stellwagen Bank National Marine Sanctuary was surveyed by using a multibeam sea-floor mapping system that utilized sound to measure the water depth and sediment characteristics as the ship steamed over the area of interest. This system provided a new and highly detailed view of the sea floor at a spatial resolution of a few meters. During the survey, the mapping system was mounted on the Canadian Hydrographic Service ship Frederick G Creed, a small waterplane twin hull (SWATH) vessel specially designed and equipped for multibeam surveying. Guided by these detailed images, we are using extensive bottom sampling and video and photographic observations to define and map biological habitats." |
| January 25, 2007 | tony (oakland) | what makes the seasons of earth | The tilt of Earth's rotational axis and the Earth's orbit work together to create the seasons. As the Earth travels around the Sun, it remains tipped in the same direction, towards the star Polaris. This means that sometimes the northern half of the Earth is pointing towards the Sun (summer), and sometimes it is pointing away (winter). These points in the Earth's orbit are called solstices. Notice that when the northern hemisphere is tilted towards the Sun, the southern hemisphere is tilted away. This explains why the hemispheres have opposite seasons. |
| January 23, 2007 | Josh (Indiana/ United States Of America) | How does an Igneous rock change to a Metemorphic rock? | The rocks are classified in three groups: Igneous rocks: formed from the cooling and solidification of magma. Sedimentary rocks: formed at the surface of the Earth from the accumulation of sediments (fragments of rocks, minerals, or animal or plant material) Metamorphic rocks: formed within the Earth's crust when other rocks (including igneous rocks!) are subjected to pressures or heat so intense that they are completely changed. For more information visit our page Rock Cycle. |
| January 22, 2007 | joni (london, england) | can you tell me what is the biggest the sun, moon or the earth | The Sun is, by far, the biggest body in our solar system. Earth is bigger than its moon. |
| January 22, 2007 | Heather (IN/U.S.) | tell me how a sedimentray rocks,and how they form. | For thousands, even millions of years, little pieces of our earth have been eroded--broken down and worn away. Sedimentary rocks form at the surface in environments such as beaches, rivers, the ocean, and anywhere that sand, mud, and other types of sediment (those little pieces) collect. They make up about three-quarters of the rocks at the Earth’s surface. They Sedimentary rocks preserve a record of the environments that existed when they formed. For more information visit our page What Is a Sedimentary Rock?. |
| January 22, 2007 | Heather (IN/U.S.) | tell me how a sedimentray rocks,and how they form. | For thousands, even millions of years, little pieces of our earth have been eroded--broken down and worn away Sedimentary rocks make up about three-quarters of the rocks at the Earth’s surface. They form at the surface in environments such as beaches, rivers, the ocean, and anywhere that sand, mud, and other types of sediment collect. Sedimentary rocks preserve a record of the environments that existed when they formed. For more information visit our page What Is a Sedimentary Rock?. |
| January 21, 2007 | Joy (Florida U.S.A) | When plates run into each other and buckle, what happens? | The potential energy stored in the system increases, and at certain point is liberated as earthquakes. |
| January 21, 2007 | adam (washington) | how is our moon's formation suposed to have been different then the formation of other planetary satelites? | In general, scientists believe that the solar system was formed when a cloud of gas and dust in space was disturbed, maybe by the explosion of a nearby star (called a supernova). This explosion made waves in space which squeezed the cloud of gas and dust. Squeezing made the cloud start to collapse, as gravity pulled the gas and dust together, forming a solar nebula. The planets and moons were formed from this solar nebula. For a description of the formation of our system, please visit our web page Solar System Formation. In the particular case of our Moon, there are three theories, more or less related to the previous description, about how the moon came to be in place: - that the moon came out of the crust of the Earth - that the moon was captured by the Earth - that the Earth and moon formed together out of the primordial nebula |
| January 19, 2007 | Sam (California) | What are the interior layers of Our Moon composed of ?(kind of minerals/rocks) | The structure of the Moon's interior is difficult to study. The Moon's top layer is a rocky solid, perhaps 800 km thick. Beneath this layer is a partially molten zone. Although it is not known for certain, many lunar geologists believe the Moon may have a small iron core, even though the Moon has no magnetic field. By studying the Moon's surface and interior, geologists can learn about the Moon's geological history and its formation. For more information, please visit our page The Earth's Moon. |
| January 17, 2007 | Rosalinda (CA - USA) | Do you know of any other (aside from Apollo 8) space flight that reached teh escape velocity FOR Earth? | All missions going in to deep space (to study other planets, for example) need to reach the escape velocity for our planet. |
| January 17, 2007 | Graciela (Arizona) | How did the moon formed | There are three theories about how the moon came to be in place: - that the moon came out of the crust of the Earth - that the moon was captured by the Earth - that the Earth and moon formed together out of the primordial nebula |
| January 17, 2007 | Graciela (Arizona) | How did the moon formed | There are three theories about how the moon came to be in place: - that the moon came out of the crust of the Earth - that the moon was captured by the Earth - that the Earth and moon formed together out of the primordial nebula |
| January 16, 2007 | tiana (macon) | why is lonosphere not on here | We have discussed the ionosphere in several of our pages: The Ionosphere, The Sun's Effect on the Ionosphere, Regions of the Ionosphere, Ionosphere Constituents, etc. |
| January 14, 2007 | Diana (Queensland-Australia) | What other types of cyclones are there apart from the tropical cyclone? | The six major types of cyclones are: Polar cyclone, Polar low, Extratropical, Subtropical, Tropical, or Mesoscale. Tropical cyclones, in particular, are also known, depending on their location and strength, as hurricane, typhoon, tropical storm, cyclonic storm and tropical depression. |
| January 14, 2007 | aivy (philippines) | is ionosphere important to our atmosphere? | The ionosphere, as the electrically charged portion of our atmosphere, is responsible for the changes that electromagnetic waves suffer when traveling through it. For example, before the first communication satellite reached orbit, we were able to communicate via radio with Europe through bouncing radio signal against the ionosphere. Similarly, the Global Position System (GPS) signals are affected when passing through the ionosphere. |
| January 3, 2007 | Eduardo (Philippines) | What is the meaning of Foliated Rocks and please give its uses | The layering within metamorphic rocks is called foliation and it occurs when a strong compressive force is applied from one direction to a recrystallizing rock. This causes the platy or elongated crystals of minerals, such as mica and chlorite, to grow with their long axes perpendicular to the direction of the force. This results in a banded, or foliated, rock, with the bands showing the colours of the minerals that formed them. Textures are separated into foliated and non-foliated categories. Foliated rock is a product of differential stress that deforms the rock in one plane, sometimes creating a plane of cleavage: for example, slate is a foliated metamorphic rock, originating from shale. Non-foliated rock does not have planar patterns of stress. For a comprehensive discussion on this topic, visit the Wikipedia web page Metamorphic Rocks. |
| December 27, 2006 | bethany (NewYork) | How did earth cometo be | Scientists believe that the solar system was formed when a cloud of gas and dust in space was disturbed, maybe by the explosion of a nearby star (called a supernova). This explosion made waves in space which squeezed the cloud of gas and dust. Squeezing made the cloud start to collapse, as gravity pulled the gas and dust together, forming a solar nebula. The planets and moons were formed from this solar nebula. For a description of the formation of our system, please visit our web page Solar System Formation. |
| December 27, 2006 | Elise (G.A) | How Far Away Is The Moon From The Sun? | Because the our Mon rotates around the earth, we can use our planet distance to the Sun: Minimum Distance from Sun: 146 million km (91 million miles) Maximum Distance from Sun: 152 million km (94.5 million miles) |
| December 27, 2006 | Ashley (plant city) | how do scientists think earth formed. | Scientists believe that the solar system was formed when a cloud of gas and dust in space was disturbed, maybe by the explosion of a nearby star (called a supernova). This explosion made waves in space which squeezed the cloud of gas and dust. Squeezing made the cloud start to collapse, as gravity pulled the gas and dust together, forming a solar nebula. The planets and moons were formed from this solar nebula. For a description of the formation of our system, please visit our web page Solar System Formation. |
| December 20, 2006 | krishnadas (kerala/india) | "I have heard that moon has a low gravitational force .Even then it is capable of attracting the Earth.Please tell me how." | The Earth's natural satellite, the Moon, is more than one quarter the size of Earth itself (3,474 km diameter). Because of its smaller size, the Moon's gravity is one-sixth of the Earth's gravity. More interesting facts about the Moon can be found in our web page The Earth's Moon. |
| December 20, 2006 | jodecy (florida) | What is metamorphic rock | The rocks are classified in three groups: Igneous rocks: formed from the cooling and solidification of magma. Sedimentary rocks: formed at the surface of the Earth from the accumulation of sediments (fragments of rocks, minerals, or animal or plant material) Metamorphic rocks: formed within the Earth's crust when other rocks are subjected to pressures or heat so intense that they are completely changed. For more information about Rock and the Rock Cycle visit our page Rocks. |
| December 20, 2006 | Cody (New Jersey/USA) | Why are meteor craters more common on the moon than on the Earth? | Because on Earth, due to the existence of the atmosphere, most asteroids vaporize before they can reach the surface. |
| December 20, 2006 | Josie (Washington, United States) | Why are there more meteorite landings on the moon then the earth when the earth is bigger then the moon? | Because on Earth, due to the existence of the atmosphere, most asteroids vaporize before they can reach the surface. |
| December 20, 2006 | kendrea (Geogetown) | what is the ozone layer | The ozone layer is the part of the Earth's atmosphere which contains relatively high concentrations of ozone (O3). It was discovered in 1913 by the French physicists Charles Fabry and Henri Buisson. |
| December 14, 2006 | hayli (Tennessee) | What is the lithosphere and the asthenosphere made of? | Together the crust and upper mantle are called the lithosphere and they extend about 80 km deep. The lithosphere is broken into giant plates that fit around the globe like puzzle pieces. These puzzle pieces move a little bit each year as they slide on top of a somewhat fluid part of the mantle |
</td>
<td>IN WHICH COUNTRIES ARE SILICATE AND NON SILICATE MINERALS FOUND?</td>
<td>Approximately 30% of all minerals are silicates (some geologists estimate that 90% of the Earth's crust is made up of silicates). They are found virtually everywhere.</td></tr>
<tr align=left valign=top><td>February 15, 2008</td><td>Ady (Indonesia)</td>
<td>We all know that the earth's interior is made of mostly molten iron.Will it cool down and eventually become solid?</td>
<td>The main source of heat in our planet ir radioactive decay. Eventually a balance will be reached and our planet will cool down.</td></tr>
<tr align=left valign=top><td>February 12, 2008</td><td>cris (washington)</td>
<td>When is the summer solstice for the N. Hemisphere in 2007-2008?</td>
<td>For the N. Hemisphere the solstice occurs begins: 2007-06-21 at 18:13, and 2008-06-21 at 00:00.</td></tr>
<tr align=left valign=top><td>February 8, 2008</td><td>Sakura (Austalia)</td>
<td>What is the likely outcome of the greenhouse effect in 100 years?</td>
<td>The answer of your question greatly depends on how Humans act now and in the near future. A continuos accumulation of greenhouse gases will be devastating for our planet.</td></tr>
<tr align=left valign=top><td>February 8, 2008</td><td>DJ (New Zealand)</td>
<td>What/who is earth named after?<br>Ta!<br></td>
<td>There are many theories about our planet name. Two of the most accepted are:
1. The word Earth came from the Latin Terra; and
2. The word Earth originates from the Middle English word, erthe, which came
from Old English eorthe.</td></tr>
<tr align=left valign=top><td>February 7, 2008</td><td>Andrew (Canada)</td>
<td>If the earth turns at a constant rate and revolves at a constant rate why is there so much variability in climate from place to place around the world?</td>
<td>Many factors affect local climates (climates influencing very small geographical areas). Examples of local climates include land and sea breezes, the orographic effects of mountains and heat island effects of cities. Other factors, like pollution and desertification, are also important for local climates.</td></tr>
<tr align=left valign=top><td>February 7, 2008</td><td>aurora (USA)</td>
<td></td>
<td>The stuff that rocks are made from has stayed the same, but the rocks themselves have not. Over time rocks are recycled into other rocks. Moving tectonic plates are the primary agents destroying and forming various types of rocks. More information in our web page <a href=){kind=link}