Shooting stars from Orion

If you can't sleep this week, try counting a few shooting stars. There will be a few more of them in the night sky than usual, especially during the wee hours of October 22. Go outside around 2 a.m. and look toward the southeast for faint, fleeting streaks of light among the stars. If you see one streaking out of the asterism forming Orion's upheld club, you'll have spotted an Orionid meteor.

The term 'meteor shower' is a misnomer. Meteors don't 'rain' down from the sky, and neither do they pelt the ground with meteorites. A meteor shower merely constitutes an increase in the number of meteors per hour that appear to emanate from a particular area of the sky, known as the radiant. In the case of the Orionids, if you track their streaks backwards across the sky, they all lead to a location in the constellation Orion the Hunter (hence the name, Orionids).

This week Orion rises in the southeast around midnight and is well up by 2 a.m. Look for its characteristic three stars in a straight row, which marks the hunter's belt. On opposite sides of the belt are two bright stars: brilliant blue-white star Rigel to the lower right or southwest, and ruddy Betelgeuse to the upper left, or northeast. The meteors appear to emerge from the hunter's club (or sword, if you prefer), which is formed by a scattering of faint stars arcing above Betelgeuse, below the feet of Gemini the Twins.

Like most meteor showers, the Orionids were spawned by ice, dust, and small stones spewed into space by a comet - Halley's Comet in this case - during its inbound journey to the Sun. The Eta Aquarids, seen in May, were also spawned by debris from Comet Halley (May 3 - 9).

You can expect to see between 10 and 30 Orionid meteors per hour on a dark moonless night. They're swift, faint, and may display color variations and persistent trains. One nice thing about the Orionids is that you can see them nearly all month. Unlike the more intense meteor showers that have sharp peaks and are spectacular for only one or two nights, the number of Orionids per hour climbs slowly from October 2 until its peak 20 days later. On days around the peak, several maxima regularly occur. After that, the numbers drop off slowly until around November 7. So, if you're vigilant, and prone to insomnia, you can expect to see a number of these shooting stars during the late night and early morning hours for the rest of the month.

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