- Comet McNaught–Russell
C/1993 Y1 (McNaught–Russell) Discovery Discovered by: Robert H. McNaught
Kenneth S. Russell
Discovery date: December 17, 1993  Alternate designations: 1994 XI
Orbital characteristics A Aphelion distance: 250 AU Perihelion distance: 0.8676 AU Eccentricity: 0.9932 Orbital period: 1430 ± 30 a Inclination: 51.59° Last perihelion: March 31, 1994 Next perihelion: 3400s
Comet C/1993 Y1 (McNaught–Russell) is a long period comet that reached a maximum magnitude of 6.5 (just below naked eye level) in early 1994. It was discovered by Robert H. McNaught and Kenneth S. Russell using the U.K. Schmidt Telescope in Australia. McNaught and Russell worked at Siding Spring Observatory and together discovered five comets between 1991 and 1995.
Its orbital period was found to be very high – initially estimated at over 1400 years.
It was noted by Francois Colas (Paris observatory)  and Ichiro Hasegawa  that the path of the comet coincided with a comet C/574 G1 recorded in AD 574 over a period from April 4 to May 23 by observers in China. This would give the comet a period of 1430 ± 30 years and so making it the longest period comet to be seen on two separate returns. Since the comet was not observed to approach any planets, its orbit should remain largely unchanged on its next return. This would place its next approach to the inner solar system in the 3400s.
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