Comets

Halley's Comet

Fast Facts:

• made up of frozen gas and dust
• normally a few kilometres in diameter
• follow an elliptical orbit
• as they approach the Sun they begin to heat up producing:
          ... a gas and dust cloud around the comet's core
          ... a tail of dust and gas that points away from the Sun
  
   

Some known comets:

• Kohoutek's Comet, orbits every 75,000 years and was first seen in 1975
• Azrond-Roland's Comet, orbits every 10,000 years and was first seen in 1957
• Humason's Comet, orbits every 2900 years and was first seen in 1961
• Donati's Comet, orbits every 2040 years and was first seen in 1858
• Ikeya-Seki's Comet, orbits every 880 years and was first seen in 1965
• Halley's Comet, orbits every 76 years and was first seen in 240bc
• Holme's Comet, orbits every 6.85 years and was first seen in 1892
• Biela's Comet, orbits every 6.7 years and was first seen in 1806
• Pons-Winnecke Comet, orbits every 6 years and was first seen in 1819
• Encke's Comet, orbits every 3.3 years and was first seen in 1786