Tuesday, 9 December 2014

Time to Enjoy the Geminid Meteors

For many many years, it was the night of August 12th that was the most looked forward to on the shooting star watcher's calendar; the night of the annual Perseid maximum.

Despite their reputation, the Perseids have many drawbacks as a spectacle. For a start, the radiant, the point in the sky from which the meteors appear to originate from, rises very late in the UK, and thus the optimum time for observing the meteors is well past midnight. Also, in mid summer, the skies are never as dark as they are in winter, and so some fainter meteors will be drowned out in the deep twilight conditions.

Thirdly, the weather has not been great the last couple of years, with the night of maximum often clouded out.

The Geminids, which will reach maximum this weekend on the night of 13th-14th December, seem to have overtaken the Perseids as the most reliable shower of the year. For a start they have a longer build up, allowing meteors to be seen in the week to ten days prior to maximum. They tend to be slower moving and brighter, and thus easier to see. The winter skies are darker and crisper, allowing fainter meteors to be seen. And finally, the radiant is already reasonably high in the sky by the early evening, and not far from overhead by midnight which makes them a spectacle children can enjoy too.

Unlike meteor showers like the Perseids and Leonids - associated with the comets Swift-Tuttle and Temple-Tuttle respectively - the source of the Geminids seems to be the asteroid Phaeton, an object with an orbit that takes it twice as close to the sun as the planet Mercury, raising its temperature to 750C in the process.

I saw my first Geminid of the 2014 season last night at about midnight, streaking through the constellations of Triangulum and Australia. Just after it did so, a pair of canada geese flew low overhead, softly glowing in the moonlight. It just went to emphasise what magical sights there are to have while meteor watching.

The best time for observing Geminids this year will probably be up to midnight - one am on the night of the 13th-14th - after this, a last quarter moon will start to interfere although plenty of brighter meteors will still be visible. Unlike the Perseids, which tend to be seen closer to the radiant, Geminids tend to wander much further across the sky. Because of this, a reclining chair with a good view of the zenith might well be the best place to watch the meteors from, although remember for the love of all that's holy to wrap up warm this time of year. A good view of the Southern portion of the sky might be best, particularly later on.

Watch for the colour of the meteors. Often Geminids will appear to have a markedly orange hue compared to the Perseids, and often they leave a smokey trail too. They may also appear to "wobble" slightly as they travel across the sky.

So lets hope for clear skies, and not too much in the way of savage frosts or numbing gales, and let us see what we shall see.

Good hunting!

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