Astronomy

2. an enormous cloud of dust and gas occupying the space between stars and acting as a nursery for new stars.
6. color of a star
8. he intrinsic brightness of a celestial object
9. a contracting mass of gas which represents an early stage in the formation of a star, before nucleosynthesis has begun.
11. color of a star
13. a star that suddenly increases greatly in brightness because of a catastrophic explosion that ejects most of its mass.

1. a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
3. color of a star
4. measure of hotness or coldness
5. the force that attracts a body toward the center of the earth, or toward any other physical body having mass.
7. the large round object that circles the Earth and that shines at night by reflecting light from the sun.
10. color of a star
12. a luminous ball of gas, mostly hydrogen and helium, held together by its own gravity.