|Discovered by||Sylvian Arend|
|Discovery date||October 4, 1951|
|1951 Q4, 1959 O4|
|Semi-major axis||4.0884 AU|
|Orbital period||8.27 a|
November 1, 2007
Comet Arend or 50P/Arend is a periodic comet in the Solar System which was discovered on October 4, 1951. It was discovered by astronomer Sylvain Julien Victor Arend at the Royal Observatory of Belgium located in the municipality of Uccle. The comet was illustrated at approximately a magnitude of 14 and also exhibited a nucleus within a coma 14 arc seconds across. From its discovery, the comet has had 7 perihelions with its last return of Earth recorded on November 1, 2007. The comet's next perihelion will be in the year 2024.
50P/Arend was observed at its brightest at a maximum magnitude of 14 when it was discovered in 1951. At the comet's next apparition on September 1, 1959, did not exceed 17 if it had not been for an outburst in November which affected its brightness to magnitude 15.5. The observed orbital period was 7.8 years at the time of its discovery however at each succeeding perihelion has led to less favorable observations due to its 0.64 astronomical units (AU) as it approached Jupiter in 1969, even if its maximum magnitude was 15. This approach also led to the comet's orbital period to increase to 8.0 years.
Long-term motion studies conducted by Brian G. Marsden on the comet 50P/Arend renders the comet's orbital eccentricity at 0.5 which makes it relatively undisturbed by Jupiter over the last 200-year cycles despite as passage of only 0.49 AU. The study was conducted inside the interval where libration happens. Several comets, namely 50P/Arend, 4P/Faye, 6P/d'Arrest, 22P/Kopff, 36P/Whipple, 78P/Gehrels, 92P/Sanguin, 4015 Wilson-Harrington, and 128P/Shoemaker-Holt, were observed at the Palomar Observatory. Visible coma activity was only observed from 4P/Faye and 50P/Arend out of the 9 other comets from data obtained in May 2000 and March 2001. There have been 1069 observations from October 8, 1951, to February 19, 2008, also where its mean residual is at 0".60.
The nucleus of the comet has a radius of 0.95 ± 0.03 kilometers, assuming a geometric albedo of 0.04.