instruction: Classify each of the following as either a planet, a star, or a galaxy:  Mercury, Venus, Polaris, Earth, Sun, Mars, Jupiter, Milky Way, Andromeda, Saturn, Virgo A, Maffei 1, Uranus, Neptune, Sirius, Vega.
response: Stars: Sun, Polaris, Sirius, Vega
  
  Planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
  
  Galaxies: Milky Way, Andromeda, Virgo A, Maffei 1