There are nine planets including the Earth, that move around the Sun, but Jupiter is the biggest planet in the Solar System. It is so big that you could fit 14 Earths inside it! If you have been outside over the last few weeks you may already have seen it without even noticing. How to find Jupiter 
Jupiter is made up of gasses - see the Great Red Spot |
Jupiter is the really bright star that is shining in the western part of the sky. To find Jupiter you need to know where the sun sets (don't look at the Sun, its very dangerous, just be aware of where it went down in the sky). Then with a responsible adult, go outside and look in the opposite direction and look up in the sky. If you are looking in the evening, then look about halfway between the horizon and the point over your head. You will see a really bright white star like object, this is not really a star, but is Jupiter. A planet made of gas Just like Saturn, Jupiter is made up of gas so there is no solid surface to stand on. If you landed on Jupiter, you would sink right into it. The planet is made up of a number of different gasses. When we look at Jupiter, we can see lots of different colours, which are caused by these different gasses. We can also see a huge tornado whirling around the giant planet. This tornado is so big that you can fit three Earths inside it and is called the Great Red Spot. 
Some of Jupiter's moons |
How many moons? If you were to look at Jupiter through a telescope you would see all these things but would also see some of its Moons. We only have one moon which we call the Moon! Jupiter has at least 30 moons but we are always finding more. An astronomer called Galileo found the first four of them and we can easily see them in small telescopes. In order of distance from Jupiter, they are: Io, Europa, Ganymedei and Callisto. If you watch them over a few hours you will even be able to see whch direction they are moving in. The moon Europa is very interesting to astronomers and other scientists because we think that underneath the icy surface there is a really deep ocean of liquid water. We are fairly certain about that but we don't know quite what the conditions are like there. A future space mission is planned to go to this moon of Jupiter and take a look. If conditions are right, then we hope that we might find some form of really simple life; perhaps like the bacteria we find on Earth. Got a question on Jupiter? Ask Mark! »
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