9781422283714

Jupiter is a huge planet, with a volume more than 1,300 times that of the Earth. But it has only about 300 times the Earth’s mass. In other words, it is much lighter for its size than the Earth is—it has a much lower density. This is how we know that it must be very different in structure from the Earth. Jupiter is too light for its size to be made of solid rock like the Earth is. It has to be made up of much lighter materials, such as gas. Studies from the Earth and by space probes have shown that Jupiter is made up mainly of the two lightest gases there are—hydrogen and helium.   Jupiter and Saturn   are great balls of   gas and liquid gas. Gas Bal ls

∆ The space shuttle’s main engines used liquid hydrogen as fuel.

∆ A look inside Jupiter and Saturn. Both planets are made up mainly of hydrogen, in the form of a liquid and a liquid metal.

Can a “submarine” from NASA explore a liquid sea on Saturn’s moon Titan?

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