Tonight & Tomorrow night -- the Geminid Meteor Shower, and it should be good!
The radiant is the perspective point where a shower's meteors would all appear to be coming from if you could see them approaching from the far distance. In reality they flash into view only when they hit Earth's atmosphere -— which can happen anywhere in your sky. But their directions of flight, if you trace them backward far enough across your sky, all cross this point. (S&T illustration)
Sky & Telescope Magazine
Cambridge Massachusetts USA, founded 1941
Tuesday 8 December 2009
Homepage Observing by Tony Flanders
A Great Year
for Geminid Meteors
The strongest and most reliable meteor showers are the Perseids of August and December's Geminids. Balmy weather and summer vacations have made the Perseids well known and popular, but the Geminids are actually easier to view from mid-northern latitudes. For one thing, nights are much longer in December. And while the Perseids are best viewed just before dawn (as most showers are), you can easily get an eyeful of the Geminids during the evening hours.
This year the Moon will be nearly new when the Geminids peak on the night of [Sunday-Monday] December 13-14. The shower's radiant, the point in the sky from which they all seem to originate, is near Castor and Pollux. It's well up in the east by 9 or 10 p.m. and crosses near the zenith (for mid-northern observers) around 2 a.m.
The shower should peak around 5:00 Universal Time on the morning of the 14th, corresponding to midnight EST and on the 13th at 9 p.m. PST — excellent timing for North America and Western Europe. Under dark-sky conditions you might see as many as 120 medium-speed meteors per hour. (Light pollution reduces the numbers.) The shower is active to a lesser extent for at least a day or two beforehand and about one day after.
The Geminid meteor shower is extremely unusual in that its parent object isn't a comet. Instead, it's an asteroid, a chunk of rock roughly 3 miles across called Phaethon (pronounced FAY-uh-ton). How can an asteroid produce meteoroids? Nobody knows for sure. Many scientists believe that Phaethon is the core of a comet that's been baked completely dry. Maybe a smaller asteroid collided with it long ago. In any case, a ribbon of debris lines Phaethon's orbit.
On December 13, 2001, Thad V'Soske of San Diego, California, caught a Geminid crossing Orion's Belt. He was using Kodak P1600 slide film at a dark-sky site near Anza-Borrego Desert State Park.
Meteor watching couldn't be easier. Lie back in a reclining lawn chair, relax, and watch the sky overhead. Ideally, you want nothing but sky in your field of view — not trees, and certainly not the ground. That means that you should either lie flat on your back or recline so that you face at least 45° above the horizon. Also remember that December nights are cold at mid-northern latitudes. Normal winter clothing won't even come close to keeping you warm after you've been lying still for a couple of hours. The best solution is to use a sleeping bag. Second best is plenty of blankets over your warmest clothing. And don't forget a hat and gloves!
The arriving Geminids will cover the whole sky, so it doesn't really matter which way you're pointed. If you look straight at the radiant, you'll see meteors coming directly toward you, bright but with short trails. Look the opposite way, and you'll see lots of long meteors moving away from you.
Careful counts of meteors have scientific value. Click here to learn how to conduct a scientific meteor count and how to report your results to the International Meteor Organization.