Tuesday, October 8, 2013

Hunter's Moon will diminish most of the Orionid meteor shower

"Hunter’s Moon to wash out 2013 Orionid meteor shower"

Earth & Sky

The October full moon – the Northern Hemisphere’s Hunter’s Moon – is (or was if you’re reading this later) on the night of October 18-19, 2013. In a bit of misfortune for meteor-watching enthusiasts, the full Hunter’s Moon happens only a few days before the expected peak date for the Orionid meteor shower. Although the Orionids will be bombarding the nighttime from midnight until dawn for the nights of October 20-22, the light from the bright waning gibbous moon is sure to wash out all but the brightest Orionid meteors. Still, moon or no moon, the most Orionid meteors are expected to fall in the wee hours before dawn on Monday, October 21. Follow the links below to learn more about the 2013 Orionid meteor shower.

When should I watch for Orionid meteors in 2013? The best time for viewing for these fast-streaking Orionid meteors will be between midnight (1 a.m. daylight time) and dawn on the mornings of October 20, 21 and 22, 2013. That time holds true no matter what time zone you’re in. If you’re in Asia, you might want to lean a bit toward the morning of October 22. In 2013, you can’t expect to see much because bright moonlight will interfere. But you might, indeed, see a very bright meteor streaking along in bright moonlight>

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 single point within Orion. The radiant point for the Orionids is above and outside Orion’s rectangle. But – again – you don’t need to identify exactly where the radiant is to enjoy the meteors, or Orion! Just go to a dark sky and look up.

What planets are visible at late night during the 2013 Orionid shower?
The planet Jupiter rises in the east at late evening, and the planet Mars rises in the east in the wee hours after midnight. Dazzling Jupiter beams to the northeast of the constellation Orion in October 2013, near the constellation Gemini’s two brightest stars, Castor and Pollux. The planet Mars shines close to Regulus, the brightest star in the constellation Leo the Lion.

What else should I watch for during the Orionid shower?
The moon will look plenty full tonight, as it lights up the nighttime again tonight from dusk until dawn, and the moon is always a beautiful sight to see. In fact, the moon will appear big and bright all through the peak nights of the Orionid shower. It’ll interfere with the Orionid shower in 2013, but, even if you don’t catch many Orionids, chances are that you’ll see the constellation Orion – the radiant of the Orionid meteor shower – on this moonlit 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.

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 in 2013? 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 25 meteors per hour, or one meteor every few minutes, during the Orionid peak. Although no moon-free night greets the 2013 Orionid meteor shower, watching even one bright meteor can make for a memorable night. Have fun, and don’t let the moon dampen your spirits.

You might get lucky and see some cool moon phenomena, by the way, such as a lunar halo. The photo at the top of this page is a halo around the Hunter’s Moon on October 29, 2012, as seen by EarthSky Facebook friend Randy Miller in Anderson, Indiana.

Bottom line: The 2013 Orionid meteor shower is expected to peak on Monday, October 21, in the hours between midnight and dawn. However, the light of the bright waning gibbous moon – just a night or two from this year’s Hunter’s Moon – will wash out all but the brightest Orionid meteors.

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