Comet Forbes was discovered by astronomer Alexander F I Forbes of Rosebank, South Africa. He discovered it through a Microscopium on 1st August, 1929. Astronomer Forbes informed the astronomers at Johannesburg about his discovery. Announcement about the discovery of a new comet was made after its confirmation on 3rd August. The comet was named as comet Forbes after the astronomer Forbes who discovered it.
Observations made about this comet include:
- Harry Edwin Wood of Union Observatory, South Africa noted about its parabolic orbit on 21st August. He also indicated a perihelion date of 26th May, 1929.
- Bernard Dawson of La Plata Astronomical Observatory, Argentina noted an elliptical orbit on September 30th. He indicated a perihelion date of 26th June, 1929.
- Dawson also added that its last perihelion was in 1923.
- The nucleus was noted at about 1.9 km in diameter.
On its discovery in August, 1929, comet 37P/Forbes was bright at a magnitude of about 11. From October onwards, it started to fade at magnitudes 14–16.5. The 1942 apparition revealed a magnitude of about 15–12. In 1999 July, it experienced a surge in its brightness at magnitude 11.
Perihelion distance (nearest to the sun) of comet 37P/Forbes is about 1.572 AU while its aphelion distance (far from the sun) is about 5.285 AU. However, these distances keep changing due to the gravitational pull of the giant planet Jupiter.
The orbital period of comet 37P/ Forbes is about 6.37 years.
Comet 37P/ Forbes was recovered on its 1942 apparition. However, it was recovered by astronomer Van Biesbroeck on a 24–inch reflector in June, 1942. Comet Forbes was again recovered on its apparition in 1961 by Elizabeth Roemer (US Naval Observatory, Arizona)
Comet 37P/ Forbes experienced three close approaches to the earth and one close approach to Jupiter in the 20th century. Similarly, it is expected to make four close approaches to the earth and one close approach to the Jupiter in the first half of the 21st century.
Comet 37P/ Forbes is expected to reach perihelion on 3rd May, 2018. Its last perihelion was on 11th December, 2011.