Comet 6P/ d’ Arrest was discovered on 28th June, 1851 by an eminent astronomer Heinrich Ludwig d’ Arrest (Leipzig, Germany). It was discovered in the constellation of Pisces. The comet appeared faint on its first observation. It was not found the next night as the sky was hazy. However, but on 30th June, the astronomer described it as large and faint. As the comet was first discovered by d’ Arrest, it was named after him.
Some of the observations about comet d’ Arrest includes:
- On the discovery of its apparition, it had a one degree long tail.
- The comet was large and appeared faint.
- A spectacular characteristic about this comet on later apparitions was the ‘sudden surge in brightness’. Its brightness increased almost about 15–40 times.
- It is visible through a large telescope due to its faintness. When bright after perihelion, it is visible through binoculars and small telescopes.
At the time of its discovery, the comet appeared faint. On its apparition in 1950, the magnitude was revealed at about 12.5. Three weeks later, it appeared very bright and a magnitude of 10.5 was noted. During the 1995 apparition, the brightness was reached at a magnitude of about 7.5–11.
The perihelion distance (nearest to the sun) of the comet d’ Arrest is calculated at about 1.3 AU while its aphelion distance (far from the sun) is noted at 5.6 AU. However, the perihelion and aphelion distances keep changing due to the perturbations caused by the gravity of the giant planet Jupiter.
Orbital period of comet d’ Arrest is noted at about 6.5 years. However, it travels on an elliptical orbit between Mars and Jupiter.
Comet d’ Arrest had a close approach to Jupiter in 1968. Also, in 1976, it had a close approach to the Sun and the Earth.
The last perihelion of the comet d’ Arrest was on 14th August, 2008 and 2nd March, 2015 respectively. However, it is expected to pass perihelion around the year 2021.