Return of the Leonids: Annual Meteor Shower Arrives This Month

In the coming days, skywatchers will likely be hearing much about the impending return of the famous Leonid meteor shower, which graces the night skies of November each year.

When most people hear through the news media of an impending meteor shower, it's likely that their first impression is of a sky filled with shooting stars pouring down through the sky like cosmic rain.

Such meteor storms have indeed occurred with the Leonids, such as in 1833 and 1966 when meteor rates of tens of thousands per hour were observed.  In more recent years, most notably 1999, 2001 and 2002, lesser Leonid displays of up to a few thousand meteors per hour took place. [Gallery: Spectacular Leonid Meteor Shower Photos]

But the 2010 version of the Leonid meteor shower is likely to be far weaker than that. In fact, the general consensus points toward rates of 15 to 20 per hour.

In addition, there is going to be a bright waxing gibbous moon that will seriously interfere with observing the early stages of the display.

However, the moon will set a few hours before sunrise when the Leonids reach their maximum. That?s good timing, as the moon will be getting out of the way just as the constellation Leo ? from where the meteors appear to emanate ? will climb high in the southeast sky.

As for when the actual peak of the shower will occur, Mikhail Maslov, a Russian meteor expert predicts maximum activity at 1511 UT (10:11 a.m. EST) on Nov. 17. 

The International Meteor Organization (IMO) is forecasting that it will take place a bit later at 2115 UT (4:15 p.m. EST) on Nov. 17, while the 2010 Observer?s Handbook of the Royal Astronomical Society of Canada says it will happen 45 minutes later at 2200 UT (5 p.m. EST). 

All three predictions suggest that central and eastern Asia will be in the best position to see the strongest Leonid activity. 

Meanwhile, for North Americans, it looks like it will be a compromise between the predawn hours of Nov. 17 (with activity on the rise) and the predawn hours of Nov. 18 (with activity on the wane).  

Viewers should count on seeing about a dozen Leonids per hour ? hopefully more. While a far cry from the meteor storms of a decade ago, it?s still better than nothing!

The Leonids are the cosmic leftovers from a comet known as Tempel-Tuttle.  

These tiny comet particles orbit the sun in a direction opposite to that of the Earth. As a result, they hit our atmosphere at exceptionally high speeds: 45 miles per second (72 kilometers per second). The results are very swift streaks of light, some of which can leave persistent trails in their wake lasting for many seconds.

We will have more to say about the Leonids in the days ahead, and on Nov. 15 we?ll publish a complete guide on how to watch for them. So stay tuned ?

• Images - The Best of Leonid Meteor Shower, 2, 3, 4, 5
• How Comets Cause Meteor Showers
• Meteors From Halley's Comet Rain Down on Earth

Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for The New York Times and other publications, and he is also an on-camera meteorologist for News 12 Westchester, New York.