Unexpected Brightening of Comet 17P/Holmes
25 October 2007Comet 17P/Holmes now makes for an unexpected sight in the night sky. In the night of 23 to 24 October the comet has brightened by an enormous factor of several hundred thousand, from a magnitude of about 17 to a magnitude of about 2.8!
This means the comet can now be readily observed with the naked eye. Although it is bright, comet 17P/Holmes does not have a distinctive tail, rather it appears as a yellowish star with a fuzzy envelope in the constellation of Perseus.
As yet, it is not clear what caused the enormous brightening of comet 17P/Holmes, but possible causes are sudden outgassing or the release of particles from the comet's nucleus.
The comet's position on the sky for the next two weeks is detailed below. For a more extensive ephemeris of the comet's position see the "related links" in the right-hand side navigation.
Discovered by Edwin Holmes in November 1892, comet 17P/Holmes is a periodic comet with an orbital period of 6.88 years. Its eccentric orbit takes the comet from 2.05 AU out to 5.02 AU from the Sun.
17P/Holmes orbital elements
|Perihelion distance (AU)||q||
|Mean daily motion (°/day)||n||
|Semimajor axis (AU)||a||
|Argument of Perihelion (°)||
|Argument of Ascending Node (°)||
Five and a half months ago, in early May 2007, comet 17P/Holmes passed through its latest perihelion at 2.053 AU from the Sun, at which time it was 2.77 AU from the Earth. Since then its distance from the Sun has been increasing but the Earth has been catching up with the comet as the Earth orbits closer to the Sun.
Over the coming two weeks, Earth will continue to close-in on the comet. Early November the distance between the comet and Earth will be at its smallest: 1.62 AU.
|Date||Coordinates (J2000.0)||Distance (AU)|
|R.A. (h m)||Dec. (°)||to Earth||to Sun|
|25.10.2007||03 52.96||+50 08.2||1.635||2.440|
|26.10.2007||03 52.08||+50 12.6||1.632||2.444|
|27.10.2007||03 51.17||+50 16.6||1.630||2.447|
|28.10.2007||03 50.22||+50 20.4||1.628||2.451|
|29.10.2007||03 49.24||+50 23.8||1.627||2.455|
|30.10.2007||03 48.24||+50 26.8||1.625||2.459|
|31.10.2007||03 47.20||+50 29.6||1.624||2.463|
|01.11.2007||03 46.14||+50 31.9||1.623||2.467|
|02.11.2007||03 45.06||+50 33.9||1.622||2.471|
|03.11.2007||03 43.95||+50 35.6||1.621||2.475|
|04.11.2007||03 42.82||+50 36.8||1.621||2.478|
|05.11.2007||03 41.67||+50 37.8||1.620||2.482|
|06.11.2007||03 40.50||+50 38.3||1.620||2.486|
|07.11.2007||03 39.32||+50 38.5||1.620||2.490|