Captured by the strong gravity of the giant planet Jupiter, the comet now called 17P/ Holmes was a part of the distant Kuiper belt. Propelled into our solar system by Jupiter, comet Holmes became a short–period comet and a member of the Jupiter family. The most noticeable characteristic of this comet is the sudden surge or an explosion of brightness it exhibits in its apparition. While exhibiting brightness on such a massive scale, the comet appears larger than the sun. However, the surge of its brightness still remains a mystery. A spectacular vision for stargazers, comet Holmes remains one of the brightest comets. Like all the other celestial bodies, it also orbits the sun. Let us understand this comet in detail.
Astronomer E. Holmes (London, England) was the first to discover this comet. Edwin Holmes was an amateur British astronomer studying the Andromeda Galaxy. On 6th November, 1892, while observing Mu Andromedae and nearby galaxy M31, he noticed a different object. The object visible in the telescope was a comet. The coma was about 5 arc minutes and its nucleus was bright. Holmes was able to determine the rough position of the comet by 7th November. He immediately reported his findings to astronomer E. W Maunder (Royal Observatory, Greenwich, England), W. H Maw (England) and Kidd (Bramley, England). After some scepticism, Kidd and Bartlett were able to see the comet with the naked eye by 8th November. By 9th November, the comet was independently discovered by T. D Anderson (Scotland) and J. E Davidson (Australia). As Edwin Holmes was the first one to discover it, the comet was named after him.
Observations made about this comet include:
- This comet was pulled into our solar plane due to the perturbations caused by the gravity of Jupiter. A sudden surge in its brightness may have led to its discovery apparition. The comet was visible to the naked eye when bright.
- In the year of its discovery, towards December, the comet appeared very large and faint and revealed more than one tail.
- The comet exhibited an explosive brightness again in January and became visible to the naked eye. Thereafter, it started to fade continuously and by March, it was extremely faint and finally, was not visible.
- The comet had a 5 arc minutes coma and the nucleus appeared bright.
- The orbits calculated were parabolic but later an elliptical orbit was calculated.
On the discovery apparition of comet Holmes in November 1892, no actual readings about the magnitude could be ascertained. Some astronomers made certain observations about the brightness. By 12th December, astronomer Kobold (Strasbourg, France) noted that the comet was next to a star of magnitude 10. By 16th January, the comet displayed a surge in its brightness and the magnitude was 8. The 2007 apparition was unique as the comet was at its explosive brightness at a magnitude of about 2.8 near the constellation of Perseus.
Perihelion distance (closest to the sun) of comet 17P/Holmes is 2.0532 AU. Its aphelion distance (far from the sun) of comet Holmes is around 5.1836 AU. These distances, however, change due to the gravitational effects or perturbations from Jupiter.
The orbital period of comet 17P/Holmes is noted at 6.88 years or 2,511 days.
Comet Holmes was recovered by astronomer C. D Perrine (Licks Observatory, California) with a 91 cm refractor on 11th June, 1899. Predictions were made for its return around April–May 1899. The comet was last detected on 21st January, 1900 by Perrine. Comet Holmes was lost after its 1906 apparition. The perihelion date predicted was 15th November, 1964. Comet Holmes was recovered by E. Roemer (US Naval Observatory, Flagstaff station, Arizona) on 16th July, 1964.
Comet 17P/Holmes had close approaches with Jupiter on 9th December, 1908, April 1968 and January 2004 and is expected to approach the planet again on 8th April, 2051.
Comet 17P/Holmes is expected to reappear on 19th February, 2021, which is its next perihelion date. The last perihelion of comet 17P/ Holmes was 27th March, 2014 and 4th May, 2007.
