Periodic comets visit us again and again. Non-periodic comets visit us only once. On this list there is a "P" in front of the periodic comets. In front of non-periodic comets there is a "C". There is sometimes a number in front of the "P": it shows the number of times people saw the periodic comet visiting us.
Comets we usually know by a name[change | change source]
- Caesar's Comet
- Comet Borrelly (19P/Borrelly)
- Comet Encke (2P/Encke)
- Comet Hale-Bopp (C/1995 O1)
- Halley's Comet (1P/Halley)
- Comet Humason (C/1961 R1)
- Comet Hyakutake (C/1996 B2)
- Comet Ikrya–Seki (C/1965 S1)
- Comet Kohoutek (C/1973 E1)
- Comet Mrkos (C/1957 P1)
- Comet Shoemaker–Levy 9 (D/1993 F2)
- Comet Skjellerup–Maristany (C/1927 X1)
- Comet West (C/1975 V1)
- Great Comet of 1807 (C/1807 R1)
- Great Comet of 1811 (C/1811 F1)
- Great March Comet of 1843 (C/1843 D1)
- Great January Comet (C/1910 A1)
- Comet Swift–Tuttle (109P/Swift–Tuttle)
Periodic comets[change | change source]
Periodic comets have a special place in astronomy, because their orbits are often the same. We know when they will visit us, and we can plan to watch them, and send space probes to look at them.
On August 24, 1994, the International Astronomical Union (IAU) standardized the way they name this type of comet. This system tells us which comet is which. The IAU chose the letter P for periodic comets and D for periodic comets that were lost or which broke into pieces. Other letters are C for non-periodic comets, and X for comets where we do not know their orbits. It uses A for objects people say are asteroids. Each name starts with a number, so two comets have the same name.