Across
- 4. the collection of large and small bodies that orbit the sun
- 7. have a central bulge from which two or more spiral arms extend
- 10. the process that produces energy in stars
- 11. planets the four planets that orbit closer to our sun
- 12. a luminous ball of gas, mostly hydrogen and helium, held together by its own gravity
Down
- 1. number of planets that orbit the sun
- 2. small bodies that orbit planets
- 3. the four planets that orbit farther from our sun
- 5. a planet is a celestial body that is in orbit around the Sun
- 6. the distance that light travels through space
- 8. space and all matter and energy in it
- 9. area of space that little matter exist