Jupiter is the fifth and largest planet in our solar system. This gas giant has a thick atmosphere, 39 known moons, and a dark, barely-visible ring. Its most prominent features are bands across its latitudes and a great red spot (which is a storm).

Jupiter is composed mostly of gas. This enormous planet radiates twice as much heat as it absorbs from the Sun. It also has an extremely strong magnetic field. It is slightly flattened at its poles and it bulges out a bit at the equator.

SIZE
Jupiter's diameter is 88,700 miles (142,800 km). This is a little more than 11 times the diameter of the Earth. Jupiter is so big that all the other planets in our Solar System could fit inside Jupiter (if it were hollow).

Jupiter has no seasons. Seasons are caused by a tilted axis, and Jupiter's axis is only tilted 3 degrees (not enough to cause seasons).

JUPITER'S MOONS
Jupiter has four large moons and dozens of smaller ones (there are 39 moons known so far). More moons are being found all the time.

Galileo first discovered the four largest moons of Jupiter, Io (which is volcanically active), Europa, Ganymede (the largest of Jupiter's moons, pictured at the left), and Callisto in 1610; these moons are known as the Galilean moons. Ganymede is the largest moon in the Solar System.

For more information on Jupiter's moons, click here.

RINGS
Jupiter has faint, dark rings composed of tiny rock fragments and dust. These rings were discovered by NASA's Voyager 1 in 1980. The rings were investigated further when Voyager 2 flew by Jupiter. The rings have an albedo of 0.05; they do not reflect very much of the sunlight that they receive.

For more information on Jupiter's rings, click here.

TEMPERATURE RANGE
The cloud-tops average 120 K = -153°C = -244°F.

DISCOVERY OF JUPITER
Jupiter has been well-known since ancient times. It is the third-brightest object in the night sky (after the moon and Venus).

COMET SL9 HITS JUPITER

An SL-9 impact site on Jupiter, July 6, 1994. Photo by Hubble Space Telescope.

Shoemaker-Levy 9 (SL-9) was a short-period comet that was discovered by Eugene and Carolyn Shoemaker and David H. Levy. As the comet passed close by Jupiter, Jupiter's gravitational forces broke the comet apart . Fragments of the comet collided with Jupiter for six days during July, 1994, causing huge fireballs in Jupiter's atmosphere that were visible from Earth.

SPACECRAFT VISITS
Jupiter was first visited by NASA's Pioneer 10, which flew by Jupiter in 1973. Later fly-by visits included: Pioneer 11, Voyager 1, Voyager 2, Ulysses, and Galileo.

JUPITER'S NAME AND SYMBOL

This is the symbol of the planet Jupiter.

Jupiter was named after the Roman primary god, Jupiter.

JUPITER ACTIVITIES
Jupiter coloring page

Find It!, a quiz on Jupiter.

Jupiter Cloze: A fill-in-the-blanks activity on Jupiter. Answers

Interactive Jupiter Puzzle

How to write a report on a planet - plus a rubric.