Earth science

3. the displacement of spectral lines toward longer wavelengths (the red end of the spectrum) in radiation from distant galaxies and celestial objects. This is interpreted as a Doppler shift that is proportional to the velocity of recession and thus to distance.
5. a very large star of high luminosity and low surface temperature. Red giants are thought to be in a late stage of evolution when no hydrogen remains in the core to fuel nuclear fusion.
6. the explosion of a star
9. the uniform microwave radiation remaining from the Big Bang
10. a region of space having a gravitational field so intense that no matter or radiation can escape.
11. an elastic wave in the earth produced by an earthquake or other means.
12. a part or aspect of something abstract, especially one that is essential or characteristic.
14. is a seismic body wave that shakes the ground back and forth in the same direction and the opposite direction as the direction the wave is moving.
15. a fixed luminous point in the night sky that is a large, remote incandescent body like the sun.

1. a nuclear reaction in which atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of energy.
2. an effort to explain what happened at the very beginning of our universe.
4. an increase (or decrease) in the frequency of sound, light, or other waves as the source and observer move toward (or away from) each other. The effect causes the sudden change in pitch noticeable in a passing siren, as well as the redshift seen by astronomers.
7. the distance between successive crests of a wave, especially points in a sound wave or electromagnetic wave.
8. he force that attracts a body toward the center of the earth, or toward any other physical body having mass. For most purposes Newton's laws of gravity apply, with minor modifications to take the general theory of relativity into account.
13. is a seismic body wave that shakes the ground back and forth perpendicular to the direction the wave is moving.