• Small bodies
  • Rocks with ice either at the surface or beneath the surface
  • Remnants from the formation of the Solar System
  • At 20 AU the tails and coma start becoming visible
  • Irregular shapes
    • Not enough mass to become spherical
  • Don't last forever
    • Lose mass
    • Break up


Parts of a comet

  • Visible coma
    • Fuzzy atmosphere around comet
    • Halo of gas, ice, and rock
    • Effects of solar radiation upon the comet's nucleus
  • Nuclei are loose collections of ice, dust, and small rocky particles a few km in size
    • Replenish the coma
  • Tail
    • Dust tail
      • Brightest part of the tail
    • Ion tail
      • Ionized gas
      • Carried outward by streams of ions emitted by the Sun
        • Pushed directly outward from the Sun

Astronomy Space