Comet Holmes, November 19, 2007. For a few days around this date the unusual Comet Holmes made a lovely sight in the night sky as it passed in front of the brightest star in the constellation Perseus. The star is called Mirfak, or Alpha Persei. In addition, to the left of the comet in this view is a fine open cluster of stars called Melotte 20.
Comet Holmes is normally inconspicuous as it glides around in its orbit, but about a month before this photograph was taken a reflective cloud of dust and gas started to expand rapidly around the comet core, and within a few days it had a volume comparable to the planet Jupiter, even though the core of the comet is probably only three or four kilometers across. By November 19th its volume was greater than the Sun! No one knows for sure why this normally quiet comet had this sudden, dramatic change in its appearance.
This photograph was published in SkyNews Magazine (Jan/Feb '08). It was also published in SkyNews Magazine (Sep/Oct '08) receiving an Editor's Choice Award for 2008.
Three weeks earlier the comet looked like this.
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