Can you see Jupiter? Even though its orbit is far beyond those of the inner, rocky terrestrial planets, its size and yellow gas-filled clouds make it very easy to see. Only the moon and Venus outshine it! Although Jupiter seems like a large planet, it would take about 1,000 Jupiters to equal the equal size of the sun. Even so, Jupiter is biggerthan all the rest of the planets in our solar system put together! Although Jupiter's most common gases are hydrogen and helium, just like the sun, it was probably not large or hot enough to ever come close to becoming a star. Have you watched the pictures of the white clouds swirling in our atmosphere on the weather channel? They show the highs and lows in our weather and sometimesthe storms moving across Earth. If you go high enough, there are rivers of air moving around the planet. The bands of color on Jupiter show the same thing. They move in opposite directions and the colors are indicators of the temperatures and the kinds of chemicals in the atmosphere. What do you think that sulfur and ammoniawould smell like? Some think it smells a lot like rotteneggs. Since the Great Red Spot circles in between the weather bands, what do you think it could be? It is an enormous storm, much larger than the hurricanes on Earth, that has been ongoing for hundreds of years. How would you know where the gas in the atmosphere ends and the planet begins? Astronomers don't believe that you would! The enormous pressure caused by its gravity turns the hydrogen close to Jupiter's rocklike core into a metallic liquid form, and the spinning planet uses this to create a huge magnet! It creates a particle shield much larger than Earth's Van Allen belt. Can you image the aurora created by this? You can see pictures on the Internetof this beautiful phenomenon that were taken by the Hubble telescope orbiting above Earth!

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All in a Line

Every two years there is an event called an opposition, when Mars and Earth's orbits bring the planets near each other and the planets and the sun form a line across the sky. How about borrowing a telescope, so that you can see the icecaps and other geological features on Mars. In about ten years, they will be even closer so you can see Mars more easily!

Years ago, some people thought the earth's moon should have been called its sister planet because it was so big. They thought Mars's moons were too small and appeared to be much older than their planet. So, what about Jupiter's moons? There are so many of them that astronomers are beginning to wonder if there shouldn't be a limit to how small a moon can be before it should be called something else. At this point a moon only needs to orbit a planet to be called a moon. Galileo used a homemade telescope to discover Jupiter's first four moons, which were named Io, Europa, Ganymede, and Callisto. If you can borrow a telescope, see if you can find them, too. These moons travel in sync with their planet. All four moons are always facingJupiter, just like Earth's moon. This is about the only thing these four moons have in common. Io has more volcanic activitythan any other body in the solar system. This constant output also gives it the newest outer layer of any moon anywhere. Just when most astronomers had decided that there was little water anywhere but on Earth, they found out that three of Jupiter's moons contain ice. They think Europa's ice might be coveringan ocean and wonder if there might be life in the water. Ganymede, which is the largest of any of the moons anywhere and larger than some planets, is also the only moon with magnetism. How many moons does Jupiter really have? Can you find the answer?

Deathly Dry

Venus and Earth are similar in size and in what they are made of, but there is a huge difference: About 70% of Earth is covered with water, while there is hardly any water on Venus! To learn just how little water, fill the empty spaces of the puzzlegrid with the scrambled letters in the shaded boxes.

HINT:

Each letter fits in the column directly underneath it, but not necessarily in the same order.