| A | B |
|---|
| sunset | apparent descent of the sun below the horizon - uppermost portion of the sun disappears below the horizon |
| sunrise | the apparent rise of the sun above the horizon - uppermost portion of the sun appears above the horizon |
| star | a large, luminous sphere made mostly of hydrogen and helium; gets most of its energy from fusion |
| solar system | atronomical group of objects consisting of a star (the sun) and all the bodies that orbit around it |
| planet | any substantial celestial body massive enough to be round and orbiting a star (the sun) |
| orbit | the path following by an object in its revolution around another body - generally circular |
| natural satellite | a naturally ocurring body that orbits a larger celestial body; a natural satellite that orbits a planet is called a moon |
| lunar | relating to the moon |
| horizon | when the earth and sky appear to join together - apparent junction |
| artificial satellite | an artificial object that orbits the Earth or celestial body - "man-made" |
| altitude | the angle between a celestial object and the horizon measure at right angle to the horizon |
