4. Mercury The planet Mercury is too small and has little gravity to have held on to an atmosphere. The surface of the planet Mercury is covered with craters. These craters have been created by ions of accidental encounters with asteroids and comets.
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6. Venus The planet Venus has long been one of the most misunderstood of all the inner planet. Like the Earth, Venus has an atmosphere. However, this atmosphere is thicker than that of the Earth, making it difficult for modern science to penetrate.
8. Earth Scientist use the Earth to study all the other planets. Since no human has ever visited another planet we have to use what we know about the Earth and try to guess what the other planets must be like.
10. Mars Mars excites scientists because its mild temperament is more like the Earth than any other planets. Evidence suggests that Mars once had rivers, streams, lakes and even an ocean.
12. Saturn Saturn is a favourite object for many observers. Its beautiful rings are 169,800 miles wide but less thick than a football field. In many ways Saturn is similar to Jupiter, but it is much smaller.
14. Jupiter Jupiter has at least 63 moons. Jupiter’s great red spot visible in the picture to the right is where a giant storm has been ragging for at least 300 years. This storm is super hurricane winds.
16. Uranus Uranus has 27 moons. Five of these moons are large and the rest are smaller. It is believed that long ago a very large object smashed into this planet. The crash was so powerful that it completely changed the direction of Uranus spin.
18. Neptune Neptune has 13 moons that we know of. Because Neptune is so far away it is difficult to see any of these worlds. Neptune has a giant storm much like the storm on Jupiter.