Shooting Stars - The Leonid Meteor Shower

November's celebrated meteors return for another dazzling show, 

 

As the days get colder and shorter, the return of the Leonid meteor shower grows closer as well. The annual shower lasts from November 10 through the 23rd and peaks before dawn November 17. Unfortunately, Full Moon arrives November 21, so its light will interfere with meteor watching until after midnight.

While it can't compete with last year's spectacular display, this year's show still promises excitement. “Observers under a dark sky can expect to see around 20 meteors per hour radiating from the constellation Leo the Lion,” says Astronomy Senior Editor Richard Talcott. “The best time to watch on the 17th comes once the Moon sets around 3 a.m. local time.”

The Leonids started out as tiny specks of dust and debris ejected by Comet 55P/Tempel-Tuttle during its countless voyages orbiting the Sun. As Earth passes through this stream of dust, the particles hit our atmosphere at about 158,000 mph (256,000 km/h), vaporizing due to air friction. This produces the streaks of light in the sky we call meteors.

“Observers occasionally see a brief increase in meteors when Earth crosses the thickest section of the comet’s debris trail, though this occurs after daybreak in North America,” says Talcott. “It may not be perfect, but the Leonids will still provide skygazers much to see this year.”

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.