6P/d'Arrest (also known as d'Arrest's Comet or Comet d'Arrest) is a periodic Jupiter-family comet in the Solar System, orbiting between Mars and Jupiter. It passed 0.15124 AU (22,625,000 km; 14,059,000 mi) from the Earth on August 12, 1976.
The comet last came to perihelion (closest approach to the Sun) on March 2, 2015, but it was in an unfavorable apparition as it had a solar elongation of less than 30 degrees from October 2014 until May 2015.
In 1991, Andrea Carusi and Giovanni B. Valsecchi (Istituto Astrofisica Spaziale, Rome), and Ľubor Kresák and Margita Kresáková (Slovak Astronomical Institute, Bratislava) independently suggested this comet was the same as a comet observed by Philippe de La Hire in 1678.
It was first observed by Heinrich Ludwig d'Arrest, in Leipzig, Germany, on 28th and 30th of June 1851.
The comet nucleus is estimated at about 3.2 km in diameter.