What you may already know: The Earth is surrounded by a vast area called space. The universe began with a big bang. Astronauts have walked on the Moon.
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What you will learn in this chapter:
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How to tell the difference between types of celestial bodies.
Some theories about how the universe began. How the Earth compares with other planets.
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Why is Pluto no longer considered a planet? What would happen if the Sun did not exist?
Can you crack this code? 1.
The first letter of each image spells out a key word that you will come across in this chapter. Use the hints provided if you need to, or revisit the Puzzler after you finish this chapter. 2.
3. 4.
Planet between Jupiter and Uranus
364 1. ___ 2. ___
Used for viewing the solar system
3. ___ 4. ___
Lumps of rock that were left over after the formation of the solar system
The machine that propels itself across the surface of Mars
