This ultraviolet image of Jupiter shows the glowing aurora in the giant planet's atmosphere above the North Pole (top) and South Pole (bottom). Click on image for full size (48 Kb) Image courtesy of J. Clarke and G. Ballester (U. of Michigan), J. Trauger and R. Evans (JPL) and NASA.

Several interesting phenomena are found at the poles of Jupiter, the largest planet in our Solar System. Three of Jupiter's four large "Galilean" moons are ice-covered and thus reminiscent of Earth's polar regions. Io, the fourth Galilean moon, has volcanoes near its poles... and "Northern Lights" in a most peculiar location!

Unlike Uranus, which is "tipped over on its side", Jupiter is pretty much an upright planet. Jupiter's spin axis, which defines the locations of its poles, is tilted just 3.1° away from vertical. That is a much smaller tilt than Earth's 23.5° angle. Only Mercury, which is tipped less than one-tenth of a degree, is more upright than Jupiter. Jupiter's magnetic field is, however, tilted a moderate amount. The giant planet's dipole magnetic field axis is tilted 9.6° away from its spin axis, which is comparable to the 11° tilt of Earth's magnetic field.

Unlike Earth, which is rocky and relatively rigid, Jupiter is a deformable ball of gas and fluids. Though Jupiter is the largest planet in the Solar System, it rotates more rapidly than any of the other planets. Its day is just under 10 hours long. Jupiter's fast spin and "squishy" consistency cause the planet to bulge outward at its equator and pull inward at the poles. Jupiter's equatorial diameter is, therefore, about 7% larger than the distance between its poles.

Jupiter has brilliant auroral light shows (like Earth's "Northern Lights"). Earth's aurora are most active during space weather "storms". Jupiter's aurora are, by contrast, a more constant and enduring feature generated by the giant planet's powerful magnetic field and intense radiation environment. As particles of radiation bombard Jupiter's polar atmosphere, generating auroral lights, they chemically alter atmospheric gases, creating a haze in the Jovian stratosphere.

Earth's poles are far colder than its tropics, but the temperatures on Jupiter do not vary with latitude. Much of Jupiter's warmth comes from internal heating instead of sunlight, so its poles are just as warm as its equator. Earth and Jupiter are alike, however, in having stormy poles: they are the only two planets so far observed to have lightning near their poles.

This picture shows Jupiter in ultraviolet "light". Can you see Jupiter's glowing aurora above the North Pole (top) and South Pole (bottom)? Click on image for full size (48 Kb) Image courtesy of J. Clarke and G. Ballester (U. of Michigan), J. Trauger and R. Evans (JPL) and NASA.

Jupiter has beautiful auroral light shows and other interesting features at its poles. Jupiter has 4 large moons and many smaller ones. Three of the four big moons are covered with ice. They remind us of Earth's polar regions. The fourth big moon is Io. It has volcanoes near its poles!

All planets have an imaginary axis that they spin around. The North and South Poles are the places where that axis pokes through the planet's surface. Some planets are tipped over on their sides. Jupiter isn't. Jupiter is almost perfectly straight up and down. It is only tilted about 3°. Earth is tilted more than 23°. Jupiter's magnetic field is tilted more than its spin axis. Its magnetic field is tilted almost 10°. That's almost the same as Earth... our magnetic field is tilted 11°.

Jupiter spins faster than any other planet in our Solar System. Jupiter is not solid rock like Earth. It is a big ball of gas and liquids. Jupiter's fast spin makes it bulge out at the equator. The diameter of Jupiter at its equator is more than the diameter between the poles.

When radiation particles hit gases in Earth's atmosphere, the atmosphere glows. That's what causes the "Northern Lights" (also called the aurora). Jupiter has aurora too. They form over both poles of Jupiter. Radiation at Jupiter's poles also affects Jupiter's atmosphere. It causes chemical reactions that change gases in the atmosphere. Some of the gases get turned into a haze near Jupiter's poles.

Earth is cold near the poles and hot near the equator. Jupiter is about the same temperature all over. That's because most of its heat comes from inside Jupiter instead of from sunlight. The poles of Jupiter are just as warm as the equator!

This picture shows Jupiter in ultraviolet "light". Can you see Jupiter's glowing aurora above the North Pole (top) and South Pole (bottom)? Click on image for full size (48 Kb) Image courtesy of J. Clarke and G. Ballester (U. of Michigan), J. Trauger and R. Evans (JPL) and NASA.

Jupiter has interesting poles. The poles of some of its large moons are interesting too. Io is one of the big moons. Io has volcanoes near its poles! The other big moons are covered with ice, like Earth's polar regions.

All planets have a pretend axis that they spin around. The North and South Poles are the places where that axis pokes through the planet's surface. Some planets are tipped over on their sides. Jupiter isn't. Jupiter is almost perfectly straight up and down. It is only tilted about 3°. Earth is tilted more than 23°. Jupiter's magnetic field is tilted more than its spin axis. Its magnetic field is tilted almost 10°. That's almost the same as Earth... our magnetic field is tilted 11°.

Jupiter spins faster than any other planet in our Solar System. Jupiter is not solid rock like Earth. It is a big ball of gas and liquids. Jupiter's fast spin makes it bulge out at the equator. The diameter of Jupiter at its equator is more than the diameter between the poles.

When radiation particles hit gases in Earth's atmosphere, the atmosphere glows. That's what causes the "Northern Lights" (also called the aurora). Jupiter has aurora too. They form over both of Jupiter's poles.

Earth is cold near the poles and hot near the equator. Jupiter is about the same temperature all over. That's because most of its heat comes from inside Jupiter instead of from sunlight. The poles of Jupiter are just as warm as the equator!