| A | B |
|---|
| Heliocentric | Sun is the center of the universe |
| Geocentric | Earth is the center of the univers |
| axis | an imaginary rod that stretches through a planet |
| constellation | a patternof stars |
| objective lens | the lens at the far end of the telescope |
| rotation | an object spinning in isolation |
| revolution | an object spinning around another object |
| star | a huge globe of hot gases that shines by its own light |
| planet | a large object that circles a start and doesn't produce its own light |
| hemisphere | half of the Earth |
| horizon | the line in the distance where the land appears to meet the sky |
| zenith | the highest point in the sky |
| Copernicus | believed that the Earth travels around the Sun |
| Galileo | first to use a telescope and discovered that the moon did not shine by its own light |
| telescope | an instrument used for viewing distant objects |
| lens | a curved piece of glass that uses light to make objects clearer or larger |
| focal point | the point at which an image comes into focus using a lens |
| mirror | a material that can reflect light and images |
| eyepiece lens | the lens in a telescope that is closest to your eye |
| Ptolemy | believed that the sun and planets circled the Earth |
