Complete the crossword, then click on "Check" to check your answer. If you are stuck, you can click on "Hint" to get a free letter. Click on a number in the grid to see the clue or clues for that number.

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2
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	4												5
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	7
								8										9
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	11		12
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	14
						15									16
	17					18					19
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 Check 

Across: 2. Stars 8-15 times the size of the Sun may end up as one of these. 4. A useful device for observing stars and galaxies. 5. This is a natural satellite of the Earth 7. Stars release a huge amount of this. 8. This provides some evidence for the expansion of the Universe 10. Another name for the 'Search for Extra-Terrestrial Intelligence' 11. Stars begin as this 13. This holds everything in the Universe together 14. If life exists on other planets it would probably need this to survive 15. At least nine of these orbit the Sun. 17. The largest object in the Solar System 18. Another name for shooting stars 20. Stars more than fifteen times the size of the sun may leave behind one of these when they 'die'.

Down: 1. Large stars explode to form one of these 3. In addition to planets, these also orbit the sun in highly elliptical orbits 6. Jupiter, Saturn, Uranus and Neptune are mainly composed of this 8. When the Sun starts to die it will expand to form one of these before collapsing to form a 16 down 9. How the Universe Began? 12. This is the sixth planet from the sun 16. When the centre of a red giant contracts it forms a planetary _______ 19. The Earth, Mars, Venus and Mercury are made of this