| A | B |
|---|
| orbit | the path of an object as it revolves around another object in space |
| revolution | the movement of an object around another object- like the Earth around the Sun |
| axis | the imaginary line that passes through Earth's center and the North and South poles, Earth rotates on its axis |
| rotation | the spinning motion of a planet on its axis- like the Earth spinning round & round |
| astronomy | the study of the moon, stars, and other objects in space |
| lunar eclipse | the blocking of sunlight to the moon that occurs when Earth is directly between the sun and the moon |
| phase | one of the different apparent shapes of the moon as seen from Earth |
| solar eclipse | the blocking of sunlight to Earth that occurs when the moon is directly between the sun and the Earth |
| eclipse | the partial or total blocking ofone object in space by another |
| geocentric | a model of the solar system in which Earth is at the center of the revolving planets and stars |
| heliocentric | a model of the solar system in which Earth and the other planets revolve around the sun |
| gas giant | the name often fviben to the first four outer planets: Jupiter, Saturn, Uranus, and Neptune |
| ellipse | an oval shapt, the orbits of the planets are this shape |
| terrestrial planet | the name often given to the four inner planets: Mercury, Venus, Earth, and Mars |
| ring | a thin disk of small ice and rock particles surrounding a planet |
| greenhouse effect | the process by whichheat is trapped in the atmosphere by water vapor, carbon dioxide, methane, and other gases that form a "blanket" around the Earth; the trapping of heat by a planet's atmosphere |
| asteroid | rocky objects revolving around the sun that are too small and numerous to be considered planets |
| moon | a natural satellite that revolves around a planet |
| comet | a loose collection of ice, dust, and small rocky particles, typically with a long, narrow orbit of the sun |
