This radar dish at the Sondrestrom Observatory in Greenland is used to study the ionosphere. Click on image for full size (65K JPEG)

Some observations of space weather phenomena are made by spacecraft. Other observations are made from the ground on or near the surface of Earth. Spacecraft have certain advantages, such as being able to observe features from different perspectives or being able to view objects in electromagnetic wavelengths (such as X-rays) that don't penetrate Earth's atmosphere. Ground based observations have advantages as well; some records (such as sunspot counts) have been collected for periods extending back in time far beyond the beginning of the space age, and ground based instruments are generally far cheaper to install and maintain than their satellite-borne counterparts.

Observing the Sun from Earth

Telescopes and other optical instruments have been used for solar observations for centuries. We have records of sunspot counts and the appearance of the solar corona during eclipses that extend far back in time. Spectroscopes help us analyze the spectral composition of sunlight, while coronagraphs provide us with views of the Sun's atmosphere between rare solar eclipses. High altitude observatories peer into the near infrared portion of the Sun's radiation.

Aurora - Southern and Northern Lights

Collisions of magnetospheric ions and electrons with atmospheric gases at high latitudes produce spectacular light shows that we know as the aurora (or Southern & Northern Lights). Auroral observations, which also extend far back in time, provide us with evidence related to the frequency and strength of space weather storms.

Monitoring the Ionosphere with Radio Waves

Electrically charged layers of Earth's atmosphere, collectively called the ionosphere, are strongly influenced by changes in space weather. Radio frequency electromagnetic waves, which are reflected or absorbed by ionospheric layers, are used in various ways to probe the ionosphere. We bounce radar signals off the ionosphere's layers, "listening" for telltale echoes; we also use radio antenna arrays called riometers to sense the extent to which the ionosphere absorbs incident natural radio noise from deep space.

Measuring Magnetic Fields around the Globe

The constantly changing Interplanetary Magnetic Field's (IMF) interplay with Earth's magnetic field causes continuous changes in the local magnetic field strengths measured on Earth's surface. A global network of magnetometers monitors the constant shifts in the components of the resultant magnetic field, allowing us to infer the state of the IMF.

This radar dish at the Sondrestrom Observatory in Greenland is used to study the ionosphere. Click on image for full size (65K JPEG)

Spacecraft help us observe and measure space weather. We also make some kinds of space weather measurements from the surface of Earth. Satellites are better for some kinds of observations. However, observations made from the ground have advantages too. Instruments on the ground are much less expensive and are much easier to fix than instruments on satellites. Also, some observations have been made from Earth for many, many years, so we have a long history of measurements. Records of sunspots are a good example of this. Observations from spacecraft, on the other hand, only go back a few decades or less.

Watching the Sun from Earth

Astronomers have used special telescopes to view the Sun for centuries. They have kept records of sunspot counts for a long time. They have also observed the Sun's corona (part of its atmosphere) during total eclipses of the Sun. Scientists also use spectroscopes, instruments that break sunlight up into different colors, to learn about the elements in the Sun. Some telescopes that are high up in mountains can even "see" infrared (IR) "light" from the Sun. Coronagraphs, instruments that make artificial eclipses, help us study the Sun's atmosphere.

Northern Lights and Southern Lights - the Aurora

When space weather storms hit Earth's atmosphere, they create a glow in the sky we call the aurora (or Southern or Northern Lights). People have observed aurora for many years. Those observations give us a record of space weather storms that goes far back in time. Aurora watchers can notice how bright an aurora is and how long it lasts. This helps us know how strong a space weather storm is.

Using Radio Waves to Observe the Ionosphere

Space weather causes changes in Earth's atmosphere. Instruments on Earth help us keep track of how the atmosphere changes. One part of the atmosphere, the ionosphere, has lots of electrically charged particles in it. Stations on the ground work with satellites to beam radio waves through the ionosphere. The particles in the ionosphere affect the radio signals, allowing scientists to measure the ionosphere. They can see how the ionosphere changes as space weather changes.

Measuring Magnetic Fields around the Globe

The solar wind carries the Sun's magnetic field, which is called the Interplanetary Magnetic Field (IMF), with it. When the IMF gets to Earth, it combines with Earth's own magnetic field. Scientists use many magnetometers around the globe to measure the combined magnetic field. When these measurements change, we know that space weather is changing, too.

This radar dish at the Sondrestrom Observatory in Greenland is used to study the ionosphere. Click on image for full size (65K JPEG)

Spacecraft help us look at space weather. We can also make some space weather measurements from the surface of Earth. Instruments on the ground are cheaper and are easier to fix than instruments on spacecraft.

Watching the Sun from Earth

Astronomers have used special telescopes to view the Sun for a long time. Remember, these are special telescopes so that scientists won't hurt their eyes (Never look directly at the Sun with your own eyes!). Using these special telescopes, scientists have noted the number of sunspots for a long time.

Scientists use coronagraphs, instruments that make artificial eclipses, to study the Sun's atmosphere.

Northern Lights and Southern Lights - the Aurora

There is a glow sometimes in the sky that we call the aurora (or Southern or Northern Lights). People have looked at aurora for many years. The Lights are made when space weather storms hit Earth's atmosphere. Aurora watchers can notice how bright an aurora is and how long it lasts. This helps us know how strong a space weather storm is.

Using Radio Waves to Observe the Ionosphere

Space weather makes changes in Earth's atmosphere. Instruments on Earth help us keep track of how the atmosphere changes. Scientists keep a close eye on one part of the atmosphere, the ionosphere. Using instruments like radars, they can see how the ionosphere changes as space weather changes.

Measuring Magnetic Fields around the Globe

Did you know that the Sun is magnetic? When solar wind leaves the Sun, it actually carries the Sun's magnetic field with it. Scientists use magnetometers all over the Earth to measure the Earth's own magnetic field and the Sun's magnetic field when it comes to Earth.