Space

4. A planet which we live in
6. Almost the exact same size as Pluto
7. Other name for "outer planets"
10. A planet closest to the Sun
12. A system of millions or billions of stars
16. The biggest planet in our solar system
17. Has 8 main rings
18. The study of everything in the universe beyond Earth's atmosphere
19. Brightest planet in the solar system and is named after ancient Rome goddess
20. An invisible force that pulls objects toward each other

1. A place in space where gravity pulls so much that even light can not get out
2. Other names for the "inner planets"
3. The coldest planet in our solar system
5. The star around which the earth moves and that provides light and heat for the earth
8. A vehicle that is designed to fly in outer space and operate there
9. The first planet from the sun and the smallest in our solar system
11. Planet that used to be part of the solar system
13. Space matter that has entered Earth's atmosphere
14. The brightest and largest object in our night sky
15. All existing matter and space considered as a whole