Giacobini-Zinner, Comet (Comet 21P/)
A short-period comet that is the parent
body of the Draconids (also known as the Giacobinids) meteor
shower; it became the first comet to be visited by a spacecraft when
the International Cometary
Explorer (ICE) flew past it at distance of 7,800 km on September 11,
1985. Every alternate appearance of the comet is favorable for observers
on Earth and can result in a visual magnitude as high as about 7. The 1946
appearance was especially noteworthy as the comet passed only 0.26 AU from
Earth in late September; it was then near magnitude 7, although it experienced
an unexpected outburst that caused it to reach magnitude 6 during the first
days of October. It was discovered by the French astronomer Michel Giacobini
(1873–1938) in 1900 and rediscovered two returns later, in 1913, by
the German astronomer Ernst Zinner (1886–1970).
| semimajor axis |
3.52 AU |
| perihelion |
1.034 AU |
| eccentricity |
0.706 |
| inclination |
31.8° |
| period |
6.61 years |
Related category
• COMETS
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