Space

4. a large cloud of gas and dust from which solar system bodies formed
6. a planet-sized, very dense, collapsed star
7. a galaxy having the visible form of a spiral
9. the natural attraction between physical bodies
11. a small mass of ice, gas, rocks, and dust revolving around the sun
13. the apparent change in the position of an object resulting from the change in direction from which it is viewed
14. the luminous phenomenon observed when a meteroid is heated by entry into the earth's atmosphere
15. the complete range of frequencies of electromagnetic waves
16. a collapsed star of extremely high density composed of almost entirely neutrons
21. a rare, extremely bright nova
23. a unified body of matter
24. any of the millions of swirling clouds of dust and hydrogen gas that eventually evolve into thermonuclear stars
25. a star of low temperature but with great luminosity

1. any of a number of celestial objects that emit immense amount of light and often radio waves
2. any of several celestial objects emitting periodic, short intense bursts of kinds of waves
3. any of numerous solar system bodies that revolve around the sun
5. a numerical measure of the brightness of a star or planet
8. the intrinsic brightness of a celestial body
10. a diagram that shows the relationship between a stars temperature and luminosity
12. a tendency to remain in a fixed condition without change
17. an apparent grouping of stars in the sky
18. a system of two stars bound together by gravity
19. a massive star in the last phase of its evolution
20. the brightest star in the sky
22. the act of liquefying or melting