Space

4. a group of stars, gases, and space dust, in the shape of a spiral
7. degree of hotness or coldness as measured on a scale
9. when two or more particles collide
11. a diagram of many stars, it shows the temperature and luminosity of the star
15. a cloud of dust and gas appears in many shapes and colors
16. an instrument for examining spectra
18. A group of stars, clouds of dust, and dust particles
20. the measure of the brightness of an object of the distance at which it is viewed

1. a galaxy that contains the solar system
2. everything we can touch, feel, sense, measure, and detect, includes living things, planets, stars, galaxies, etc.
3. an explanation that shows the origin of stars, planets, and galaxies
5. a repeated variation in some measure
6. a unit to measure temperature
8. have no particular shape
10. any natural body outside of the earth's atmosphere
12. the amount of light received from the object
13. brightness level, light
14. older and give off less light than other galaxies
17. a ball of gas, light, and energy
19. the distance between two peaks of the wave