The solar system

3. Way Our Galaxy. (The word "Galaxy" actually means milky way in Greek).
5. An imaginary straight line on which an object rotates.
6. radiation Weak microwave radiation coming from space in all directions. It is believed to be the remnant of the Big Bang.
9. A small, frozen mass of dust and gas revolving around the sun.
12. A sensitive radiation detector.
15. Region around an object where the influence of the object's magnetic field can be felt.
17. The outermost part of the Earth's atmosphere.
20. lights seen over the polar regions which are caused when energized particles from the Sun react with the Earth's magnetic field.

1. The hazy-looking patch surrounding the nucleus of a comet.
2. star A star which is actually made up of two stars orbiting each other.
4. Year The distance which a ray of light would travel in one year. This is about 6,000,000,000,000 (6 trillion) miles.
7. The gaseous area surrounding a planet or other body.
8. star which suddenly flares up to many times its original brightness before fading again.
10. When our view of one object in the sky is blocked by either another object or the Earth's shadow.
11. When the Moon is more than half full, but less than completely full.
13. March 21st and September 22nd. Twice a year when the day and night are the same amount of time all around the world.
14. A shooting star, observed when a particle of dust enters into the Earth's atmosphere.
16. A rock, or Minor Planet orbiting the Sun.
18. The path one object takes around another.
19. A group of stars, gas and dust held together by gravity.