Unit 3 Vocab

2. a nuclear reaction in which atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of energy.
3. gaseous cloud from which, in the so-called nebular hypothesis of the origin of the solar system
7. the circular movement of an object around a central line
9. small rocky body orbiting the sun.
10. an enormous cloud of dust and gas occupying the space between stars and acting as a nursery for new stars.
12. doughnut-shaped region of icy bodies extending far beyond the orbit of Neptune.
15. the theory that the solar and stellar systems were developed from a primeval nebula

1. the magnitude of a celestial object as it is actually measured from the earth.
4. a small body moving in the solar system that would become a meteor if it entered the earth's atmosphere.
5. the magnitude (brightness) of a celestial object as it would be seen at a standard distance of 10 parsecs.
6. the motion of an object around a point, especially around another object or a center of mass.
8. Earths eccentricity,obliquity and precession
11. a measure of the amount by which it deviates from a circle
13. a celestial object consisting of a nucleus of ice and dust and, when near the sun, a “tail” of gas and dust particles pointing away from the sun.
14. each planet's orbit about the Sun is an ellipse