| A | B |
|---|
| constellation | a star picture |
| axis | imaginary rod that stretches through a planet |
| revolution | an object spinning around another object |
| hemisphere | 1/2 the Earth |
| rotation | a planet spinning on its axis; an object spinning in isolation |
| star | a huge globe of hot gases that shines by its own light |
| planet | a large object that circles a star and doesn't product its own light |
| horizon | the line in the distance where the land appears to meet the sky |
| zenith | the highest point in the sky; the point directly up in the sky |
| lens | a curved piece of glass, or other material like glass, that brings light rays closer together or farther apart so that things are shown to be clearer, larger or closer |
| focal point | the point at which the lenses of a refracting telescope bring a image to focus |
| mirror | a material that can reflect light and images |
| eyepiece lens | the lens at the eye of a telescope |
| objective lens | the lens at the far end of a telescope |
| refracting telescope | a telescope in which light from an object is gathered and focused by a lens |
| reflecting telescope | a telescope in which light from an object is gathered and focused by a mirror |
| convex | shaped in an outward curve |
| telelscope | an instrument used for viewing distant objects |
| heliocentric | a correct theory that the sun is the center of our solar system; Earth revolves around the Sun |
| geocentric | the theory that the Sun is the center of our solar system; it stated that the sun revolves around Earth |
| Ptolemy | an early astronomer who believed in the geocentric theory |
| Copernicus | astronomer who was responsible for the heliocentric theory |
| Galileo | early astronomer who first used a telescope to study the night sky |
