1. asteroid-small rocky object that revolves around the sun in an area between the inner and outer planets.
2. convection zone-part of the sun in which energy is transferred by flowing gases.
3. equinox-time of the year when the sun’s direct rays strike the equator.
4. gravity-universal force that attracts all objects that have mass toward one another.
5. lithosphere-Earth’s rigid outer layer.
6. maria-flat plains on the Moon’s surface formed from lava flows.
7. orbit-path that an object takes as it travels around another object.
8. solar eclipse-when Earth moves into the Moon’s shadow.
9. solar system-a star and the planets, moons, and other objects that revolve around it.
10. solstice-time of the year when the sun’s direct rays strike Earth farthest north or South of the equator.
11. star-huge sphere of glowing gases that gives off heat and light.
12. tide-the regular rise and fall of the ocean’s surface.
13. Astronomers- scientists that study space.
14. Gravity-is the universal force that attracts all objects.
15. Galaxy-is a giant collection of gas, dust, and billions of stars.
16. Satellites-are objects in space that orbit other larger objects.
17. Meteorites-are meteoroids that reach a planet's surface.
18. Hydrosphere-is all of Earth's water.
19. Meteoroids-space rocks.
20. Universe-is all of space, including all the energy and matter in it.
21. Comet - chunks of ice, rock and frozen gas the orbit the Sun.