Across
- 5. walked on the moon in 1968
- 9. object that revolves around another object in an orbit
- 11. this type of magnitude measures the amount of light received on Earth
- 15. The Milky way is this type of galaxy
- 20. A star system has at least ____ stars
- 21. surface is frozen nitrogen
- 22. a large cloud of contracting gas and dust
- 23. built by 16 nations and has been manned every day since 2000
- 25. most galaxies are moving away from each other, which means the universe is ____.
- 26. known as the red planet
- 27. has at least 60 moons
- 29. Earth is thought to be the center of the solar system in this model
- 30. astronimical units
Down
- 1. during these phases more of the moon's near side is lit each night
- 2. this type of magnitude measures the amount of light a star gives off
- 3. a huge group of stars, systems, clusters, dust and gas
- 4. A path around the sun
- 6. one complete revolution of Earth around the sun takes this long
- 7. A star is ____ when nuclear fusion starts
- 8. dark flat areas on the moon formed from lava 3-5 billion years ago
- 10. when Earth or the moon cast a shadow on the other
- 12. the different forms the moon takes in its appearance from Earth
- 13. at the end of a mission the shuttle can return to Earth and land like a ___.
- 14. when Earth is not leaning toward or away from the sun
- 16. during these phases less of the illuminated half of a moon is visible
- 17. ususually come from comets and astroids
- 18. day and night are causd by Earth's _____ on its axis
- 19. all objets are attracted to each other by the force of ___
- 24. First planet closest to the sun
- 28. the Earth's motion around the sun causes the ____ to change