Posted in MiARD

Have you ever seen a comet? They’re not as rare as some people think, although really bright naked-eye visible comets may only occur once a decade or so. This New Year’s eve provides a chance to easily find  the comet 45P/Honda-Mrkos-Pajdusakova, discovered in 1948 and orbiting the Sun once every five and a quarter years,  – but only with binoculars. The comet will be close to the moon on the evening of Saturday 31st December: for a sky chart indicating where to look, see and enter the information for your location and viewing time.

As an alternative to using binoculars, try using a digital camera with a long exposure pointed in about the right direction (since you may not be able to see the comet in the viewfinder) e.g. 10 s, focused to infinity or on the moon, supported on a tripod or bean bag or similar. Stars should appear as more or less sharp pin-points or short lines (due to the Earth’s rotation), the comet will be a fuzzy blob, streaks will be due to aircraft, satellites (reflecting sunlight) or meteors (also known as ‘shooting stars’). More information here on using a digital camera for astrophotography.

The comet 45P is noteworthy because in 2011 it passed quite close to the Earth (‘only’ nine million kilometers, or 0.06 AU, distant) and became one of the few comets to have been observed by radar. On New Year’s eve, the comet is expected to have an apparent magnitude (or brightness) of about 6, about the limit to be able to see a star naked-eye. For comparison, the comet Hale-Bopp which was one of the brightest comets in the last few decades, had a peak magnitude in 1997 of about -1. Because the ‘magnitude’ scale of brightness is logarithmic, this means that comet Hale-Bopp was over six hundred times brighter than is expected for 45P this time around. Comet Hale-Bopp was actually visible to the naked-eye for over 18 months, and was one of the brightest comets seen since the 18th century.

Other bright comets in the last thirty years have included Hayakutake and West.

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