Peak night for Orionid meteors?

Image top of post: Aurora, with Orionid meteor falling above it, by Tommy Eliassen Photography in Norway.

Tonight – October 20-21, 2018 – might be the peak night for the annual Orionid shower. Tomorrow before dawn (October 21) should feature a good number of meteors in this annual shower. But this year, in 2018, the bright moon is out for much of the night. You should have some moon-free viewing before dawn, but how much depends on where you live. Click here to find out when the moon sets in your sky, remembering to check the Moonrise and moonset box. Follow the links below to learn more:

When should I watch for Orionid meteors?

How many meteors can I expect to see?

Where is the radiant point for the Orionid meteor shower?

What else should I watch for during the Orionid shower?

When should I watch for Orionid meteors? Meteor showers aren’t just one-night events. In fact, they typically last several weeks, as Earth passes through a stream of debris left behind by a comet, in this case, the famous Comet Halley. According to the International Meteor Organization (IMO), the Orionids often exhibit several lesser maxima, so meteor activity may remain more or less constant for several nights in a row, centered on a peak night.

So, before dawn on October 22, the Orionids might match – or nearly match – before dawn on October 21. The Orionid meteors generally start at late night, or around midnight, and display maximum numbers in the predawn hours. That’s true no matter where you live on Earth, or what time zone you’re in. If you peer in a dark sky between midnight and dawn on October 21 or 22, you’ll likely see some meteors flying. Some might be bright enough to overcome the moonlit glare.

How many meteors can I 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! In a dark sky, you might see about 15 meteors per hour, or one meteor every few minutes, during the Orionid peak.

The Orionids radiate from a point near the upraised Club of the constellation Orion the Hunter. The bright star near the radiant point is Betelgeuse.

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.

Also, extend Orion's Belt in a southeast direction to locate Sirius, the brightest star of the nighttime sky.

While looking for the Orionid’s radiant, know that you can extend Orion’s Belt to locate Sirius, the brightest star in the sky.

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.

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Possible Orionid meteor moving by the Gemini stars Castor and Pollux. The constellation Orion the Hunter is found at the upper right and the star Sirius below Orion’s Belt. Image via Mike Lewinski

Bottom line: The Orionid meteor shower should provide a decent sprinkling of meteors between midnight and dawn on October 21.

Bruce McClure