Tonight (October 21-22, 2015) features what might be the peak night of the annual Orionid shower. The Orionid meteors generally start at late night, or around midnight, and display peak numbers in the predawn hours. Meteor showers aren’t just one-night events. In fact, they can last for several weeks, as Earth passes through a stream of debris left behind by a comet, in this case, the famous Comet Halley. If you peer in a dark sky between midnight and dawn on this night, it’s likely you’ll see some meteors flying.
Best of all, it’s very close to new moon right now! That means no moonlight to wash out the Orionid meteors in tonight’s sky.
When should I watch for Orionid meteors? The best time for viewing for these fast-streaking Orionid meteors is between midnight and dawn. That time holds true no matter what time zone you’re in. In 2015, virtually no moonlight will interfere during predawn hours, as the waxing moon sets before the peak hours of the shower.
Where is the radiant point for the Orionid meteor shower? The radiant point for the Orionids is in the northern part of Orion, near Orion’s club. Many see the Hunter as a large rectangle. You’ll surely notice its distinctive row of three medium-bright stars in the middle: those stars represent Orion’s Belt. The brightest star in the sky, Sirius, is to the southwest of Orion on the sky’s dome, and the Belt stars always point to Sirius. This constellation is up in the southeast in the hours after midnight and it’s high in the south before dawn. We will have much more to say about Orion in the months to come, because it’s one of winter’s most prominent constellations. Do you need to know Orion to see the meteors? Nah. The meteors appear in all parts of the sky. But if you trace the paths of the meteors backwards, you’ll see they all seem to come from this constellation.
What should I watch for during the Orionid shower? If you’d like to make a new friend, or revisit an old one, enjoy the company of the constellation Orion – the radiant of the Orionid meteor shower – on this dark night. Orion rises in the east at late evening, fairly close to midnight. Surrounding Orion are the bright stars typically associated with winter evenings in the Northern Hemisphere. There are many bright stars in this part of the sky, and they are beautiful, and colorful. Want to try to identify some? Your best bet is a planisphere. Also, look for Venus, Jupiter, Mars and Mercury in the predawn/dawn sky on these October 2015 mornings.
What is the origin of the Orionid meteors? Earth crosses the orbit of the famous Comet Halley every year in October. The meteors are debris from this comet that enter Earth’s atmosphere and vaporize as they fall.
How many meteors can you expect to see? The number of meteors you’ll see in any meteor shower always varies greatly depending on when and where you watch. Meteor showers are not entirely predictable. That’s the fun of them! At most – on a moon-free night – you might see about 20 meteors per hour, or one meteor every few minutes, during the Orionid peak. The dark skies make 2015 a favorable year for watching the Orionid meteors tonight, between midnight and dawn!
Bottom line: The Orionid meteor shower should provide a decent sprinkling of meteors between midnight and dawn on October 22.