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Copy the worksheet into your books. Fill in the gaps using the words given below in the word list.
There are__________general types of planet in the Solar System; they are called the__________planets like Venus, which are__________ to the Sun and consist mainly of rock, and the Gas Giant planets like__________, which are further away from the Sun and are made from__________, Hydrogen and Helium. Liquid ammonia has also been detected on Saturn. Many of the planets have__________which are natural __________orbiting each planet. All of the planets and their associated moons__________ the Sun.
Both the size of the__________and the size and__________of moons orbiting each planet varies__________the Solar System. For example __________planets like the Earth and__________have few or no moons, whereas Jupiter and Saturn which are__________have__________ moons. There are no rules that predict how many moons a planet should have, but normally the bigger the planet the__________moons it will have. This rule is not always true, Saturn is smaller than Jupiter but it has more moons; Mars is smaller than the Earth, but it has two moons whereas the Earth only has__________ Both the Moon and Charon (Pluto's moon) are very unusual natural satellites, because they both spin at exactly the same rate as their parent planet. As a result the same side of these moons is always facing the planet. You never see the other side; the dark side of the Moon.
Jupiter is a very unusual planet and has been studied by astronomers and scientists for a very long time. It has twice the__________ of all the other planets put together and its composition of Hydrogen with some Helium, suggest it could have once been a small __________ like our Sun that never started burning.
The Giant Red__________ is believed to be a storm of swirling frozen gases, mainly ammonia. Scientists also believe that Jupiter, because of its large mass and very strong gravitational pull, prevents lots of meteors from hitting the__________. Meteor impacts cause__________and could __________ life on Earth. The four largest moons of Jupiter, lo, Europa, Ganymede and Callisto were discovered in 1610 by Galileo. They are often called the__________ moons. Ganymede is the largest moon in the Solar System.
Gravity is the major force in astronomy. It is gravity that holds the Solar System together. The planets orbit the Sun because the Sun is the__________ object in the Solar System. As you move further away from the Sun the gravitational effect of the Sun__________. Thus, the closer a planet is to the Sun, the smaller the orbit of the planet and the less time it takes for it to go around the Sun. Gravity also governs moons orbiting the planets. The further away from a planet a moon is the__________ it takes to orbit the planet. The two moons of Mars, Deimos and Phobos are very small and are believed to be small asteroids captured by Mars' gravitational field.
WORD LIST
Two, moons, more, terrestrial, orbit, throughout, satellites, one, number, planets, Saturn, close, frozen, many, Pluto, small, star, large, Earth, mass, destroy, biggest, longer, decreases, spot, craters, Galilean.
