Unit 3 Vocabulary

5. A planet, machine, or moon that orbits a star or planet.
7. Deformation of a body caused by the gravity of another body. Happens on Earth with the ocean.
8. Unmanned device used to gather information and explore space.
11. The explosion of a star.
16. When the new or full moon, the Earth, and the sun are in a straight line, their tidal forces combine and create higher tides than normal.
19. When the moon and the sun are at right angles to Earth their tidal forces counteract creating lower tides than normal.
20. Device used to magnify far away objects so we can see them.
22. The force that keeps Earth in orbit.
23. When a body emitting radiation's velocity is not zero relative to an observer then the wavelength emitted changes.
24. The process that powers stars, when two atoms combine.
25. Natural luminous body, our sun is one.
26. A device used to measure the spectrum of light.

1. Space and everything it includes.
2. A giant cloud of gas and dust that is a nursery for new stars.
3. The path of an object around a point in space.
4. A place with gravity so strong that light cannot escape.
6. Plot of stars showing the relationship between their luminosities and temperatures.
9. The theory that states that our universe began as an infinitely dense and hot point that rapidly expanded and cooled and is still expanding today.
10. What forms when stars like the sun run out of fuel and expel their outer layers, leaving only their hot cores behind.
12. In one year, the distance light travels.
13. A measure of the pull of gravity on an object.
14. The amount of matter in an object.
15. The large barred spiral galaxy that we live in.
17. A disc of gas surrounding a young star that may form planets.
18. A collection of dust, gas, and billions of stars and their solar systems.
21. A spectrum of radiation emitted from a source.