| Term | Definition |
|---|
| geocentric system | A description of the solar system in which all of the planets revolve around Earth |
| heliocentric system | A description of the solar system in which all of the planets revolve around the sun |
| solar system | A large planetary system that consists of a combination of many smaller planetary systems and objects |
| ellipse | An elongated circle, or oval shape; the shape of the planets' orbits |
| inertia | The tendency of a moving object to continue in a straight line or a stationary object to remain in place |
| gravity | The force that pulls objects toward each other |
| nuclear fusion | The combining of two atomic nuclei to produce a single larger nucleus as when two hydrogen atoms join together to form helium, releasing energy |
| core | The central part of the sun, where nuclear fusion occurs |
| photosphere | The inner layer of the sun's atmosphere |
| chromosphere | The middle layer of the sun's atmosphere |
| corona | The outer layer of the sun's atmosphere |
| solar wind | A stream of electrically charged particles produced by the sun's corona |
| sunspot | A dark, cooler region on the surface of the sun. |
| prominence | A loop of gas that protrudes from the sun's surface, linking parts of sunspot regions |
| solar flare | An explosion of hydrogen gas from the sun's surface that occurs when loops in sunspot regions suddenly connect |
| terrestrial planets | The name given to the four inner planets: Mercury, Venus, Earth and Mars |
| rotation | The spinning motion of a planet about its axis. |
| revolution | The movement of an object around another object |
| retrograde rotation | The spinning motion of a planet from east to west, opposite to the direction of rotation of most planets and moons |
| greenhouse effect | The process by which heat is trapped in the atmosphere by water vapor, carbon dioxide, methane, and other gases that form a "blanket" around the earth. |
| gas giants | The name given to the first four outer planets: Jupiter, Saturn, Uranus, and Neptune |
| comet | A ball of ice and dust whose orbit is a long, narrow ellipse |
| asteroid | Objects revolving around the sun that are too small and too numerous to be considered planets |
| asteroid belt | The region of the solar system between the orbits of Mars and Jupiter, where many asteroids are found |
| meteoroid | A chunk of rock or dust in space |
| meteor | A streak of light in the sky produced by the burning of a meteoroid in Earth's atmosphere. |
| meteorite | A meteoroid that has hit Earth's surface. |
| satellite | Any object that revolves around another object in space |
| geosynchronous orbit | The orbit of a satellite that revolves around Earth at the same rate that Earth rotates |
Combine with other sets
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