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Orionid meteor shower on night of October 20-21

Halley's Comet at its 1910 visit.  The famous astronomer Edward Emerson Barnard at Yerkes Observatory in Wisconsin took this photo.

Tonight for October 20, 2015

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.

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.

Tonight and tomorrow night … October 20 and 21, 2015 … present the probable best nights of the annual Orionid meteor shower. And an awesome shower it is! For one thing, it stems from debris from the most famous of all comets, Comet Halley. In fact, the object in the picture at the top of this isn’t a meteor. It’s Comet Halley itself at its 1910 visit. The comet last visited Earth in 1986 and will return next in 2061. Debris in the orbit of this comet – the Orionid meteor stream – is now encountering Earth’s atmosphere. The meteors will become visible, starting at late evening, and usually put on their greatest display in the dark hours before dawn on October 21 and 22. At the peak, from a dark site, you might expect to see about 10 to 20 meteors per hour.

The meteors – vaporizing bits of comet ice and dust – will look like streaks of light in the night sky. They’re sometimes called shooting stars.

As is standard for most meteor showers, the best time to watch this shower will be between the hours of midnight and dawn – regardless of your time zone.

Fortunately, in 2015, the first quarter moon sets in the late evening or near midnight on October 20, leaving the morning hours dark for meteor watching. Also, in the predawn and dawn sky, look for Sirius, the sky’s brightest star. And the planets Venus and Jupiter are also very bright – brighter than Sirius – and visible in the sky before dawn.

The planets Venus, Jupiter and Mars rise several hours before dawn's first light whereas Mercury climbs over the horizon as darkness first gives way to morning twilight.

The planets Venus, Jupiter and Mars rise several hours before dawn’s first light whereas Mercury climbs over the horizon as darkness first gives way to morning twilight.

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Photo from Goldpaint Photography of the 2011 Orionid meteor shower at Middle Falls, near Mount Shasta, California. It’s a composite consisting of every meteor captured during the night and includes the Milky Way crashing into the illuminated falls. The image was Grand Prize Winner of Outdoor Photographer Magazine’s 3rd Annual Great Outdoors Photography Contest and published in their July 2012 issue. Notice there is more than one shower happening here. More from Goldpaint Photography here.

As Comet Halley moves through space, it leaves debris in its wake that strikes Earth’s atmosphere most fully around October 20-22, every year. The comet is nowhere near, but, around this time every year, Earth is more or less intersecting the comet’s orbit.

If the meteors originate from Comet Halley, why are they called the Orionids? The answer is that meteors in annual showers are named for the point in our sky from which they appear to radiate. The radiant point for the Orionids is in the direction of the constellation Orion the Hunter. Hence the name Orionids.

Even one meteor can be a thrill. Bring along a blanket or lawn chair – after midnight or before dawn – and lie back comfortably while gazing upward. Although a somewhat modest shower, these swift-moving meteors are sometimes bright, occasionally leaving a persistent train – a glowing streak that lingers momentarily after the meteor has gone!

Bottom line: Best nights for the Orionid meteor shower in 2015 are October 20-21 and 21-22, especially between midnight and dawn. You might see as many as 15 to 20 meteors per hour from a dark site.

Photo top of post: Halley’s Comet at its 1910 visit, by Edward Emerson Barnard at Yerkes Observatory in Wisconsin.

EarthSky’s meteor guide for 2015

How high up are meteors?

How do astronomers predict meteor showers?

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