How Comets Work

Observing Comets

Many comets are actually discovered by amateur astronomers. To look for comets, here are things to keep in mind:

  • Go to a place where there are few lights.
  • Learn what a comet looks like (observe as many comets as you can) and what a comet does not look like (observe other deep sky objects because they also appear as small fuzzy objects).
  • Use binoculars or a telescope (low magnification, 20-40x).
  • Look toward the east about 30 minutes before sunrise or to the west about 20 minutes after sunset because comets are often spotted by their tails.
  • Sweep the sky slowly near the horizon.

Comets will appear as small, fuzzy objects. This type of observing takes discipline, long hours and patience. On average, comet hunters spend several hundred hours of observing time to find a new comet. However, comets are named after their discoverers, so many people think it is worth the effort. For a discussion of comet hunting, consult The Sky: a User's Guide by David H. Levy, who has discovered several comets including comet Shoemaker-Levy 9 that hit Jupiter.


Comet FAQ

What is the most famous comet in history?
Many consider 1P/Halley to be the most famous comet in history. According to NASA, because of Halley, astronomers determined that comets make repeat trips around the sun.
What are the five parts of a comet?
A comet is made up of five parts: the nucleus, the coma, the hydrogen envelope, the ion tail, and the dust tail.
Which is the biggest comet?
According to the Royal Astronomical Society, Comet C/2006 P1, also known as McNaught, is the biggest comet that astronomers have encountered. It took the Ulysses space probe 18 days to traverse the solar wind surrounding the comet.
What does a comet do?
Comets are thought to orbit the sun in either the Oort cloud or Kuiper belt. When another star passes by the solar system, its gravity pushes the Oort cloud and/or Kuiper belt. This causes comets to descend toward the sun in a highly elliptical orbit with the sun at one focus of the ellipse.
How many comets are there?
According to NASA, there are 3,701 known comets.
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