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| Astronomy Essentials on Oct 19, 2014

Everything you need to know: Orionid meteor shower

In 2014, the annual Orionid meteor shower is expected to rain down the greatest number of meteors before dawn on October 21, perhaps as many as 20 meteors per hour.

In 2014, the annual Orionid meteor shower is expected to rain down the greatest number of meteors before dawn on October 21, perhaps as many as 20 meteors per hour. But the hours between midnight and dawn on the mornings of October 20 and 22 may offer a decent sprinkling of meteors as well.

What are the prospects for the 2014 Orionid shower?

When is the best time to watch for the Orionids?

Where do I look in the sky to see the Orionids?

How many Orionid meteors will I see?

What are meteors, anyway?

View larger. | Depending on the quality of your sky, you can sometimes see many interesting celestial sights in bright moonlight.  Our friend Cattleya Flores Viray in San Diego captured the moon, Jupiter and a meteor in this photo.  You can also clearly see the Pleiades star cluster in this photo.  Thanks, Cattleya!

View larger. | Depending on the quality of your sky, and on what’s up, you might see some interesting celestial sights in bright moonlight. Our friend Cattleya Flores Viray in San Diego captured the moon, Jupiter and a meteor in this photo. You can also clearly see the Pleiades star cluster in this photo. Thanks, Cattleya!

What are the prospects for this year’s Orionid shower? In short, the prospects are good because there’s little or no moon to wash out the meteors this year. Find a dark sky for the 2014 Orionids, lie down on a reclining lawn chair in comfort and look up! Give yourself at least an hour of watching time for meteors tend to come in spurts, and are interspersed by lulls. Remember, also, that it takes about twenty minutes for your eyes to adapt to the dark.

When is the best time to watch for the Orionids? As with most (but not all) meteor showers, the best time to watch the Orionid shower is between the hours of midnight and dawn. The Orionids don’t really begin to streak the nighttime sky until late evening, when the magnificent constellation Orion ascends over the eastern horizon. After their radiant point rises, you see many more meteors, and as the radiant rises higher in the sky throughout the night, the meteors will increase in number. That’s why the wee hours before dawn are usually the best.

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.

Where do I look in the sky to see the Orionids? Yes, 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 famous constellation Orion the Hunter. Hence the name Orionids.

If you trace the paths of these Orionid meteors backward, they seem to come from the Club of Orion. You might know Orion’s bright, ruddy star Betelgeuse. The radiant is north of Betelgeuse.

But you don’t need to know this constellation to see the meteors. The meteors often don’t become visible until they are 30 degrees or so from their radiant point – and remember, they are streaking out from the radiant in all directions. So the meteors will appear in all parts of the sky.

That’s why it’s best to find a wide-open viewing area than to look in any particular direction. Sometimes friends like to watch together, facing different directions. When somebody sees one, they can call out “Meteor!”

How many Orionid meteors will I see? The word shower might give you the idea of a rain shower. But few meteor showers resemble showers of rain. The Orionids are a relatively modest shower, offering about 10 to 20 meteors per hour.

Meteor showers are more subtle than rain showers, and the Orionid shower isn’t as rich a meteor shower as, for example, the Perseids in August or the Geminids in December. But the dark skies make this year’s orionid meteor shower worth watching!

Orionid meteors are known to be fast and usually on the faint side. But the Orionids can sometimes surprise you with an exceptionally bright meteor – one that would be visible, even in a light-polluted city – that might break up into fragments.

For me … even one meteor can be a thrill. But you might want to observe for an hour or more, and in that case the trick is to find a place to observe in the country. Bring along a blanket or lawn chair and lie back comfortably while gazing upward.

This is the famous Comet Halley. Orionid meteors are debris left behind in its orbit.

What are meteors, anyway? Meteors are fancifully called shooting stars. They aren’t really stars. They’re space debris burning up in the Earth’s atmosphere.

The Orionid meteors are debris left behind by Comet Halley. The object at left isn’t a meteor. It’s that most famous of all comets – Comet Halley – which last visited Earth in 1986. This comet leaves debris in its wake that strikes Earth’s atmosphere most fully around October 20-22, while Earth intersects the comet’s orbit, as it does every year at this time.

Particles shed by the comet slam into our upper atmosphere, where they vaporize at some 100 kilometers – 60 miles – above the Earth’s surface.

The Orionids are extremely fast meteors, plummeting into the Earth’s atmosphere at about 66 kilometers – 41 miles – per second. Maybe half of the Orionid meteors leave persistent trains – ionized gas trails that last for a few seconds after the meteor itself has gone.

Bottom line: In 2014, the Orionid meteor shower is expected to rain down its greatest number of meteors on the morning of October 21. The day before or after might feature meteors, too. Fortunately, in 2013, the thin lunar crescent rising shortly before sunrise won’t intrude on this year’s Orionid meteor shower!

EarthSky’s meteor shower guide for 2014