The "magic hour" for Geminid meteors
As arctic air and record cold sweeps across the USA, amateur astronomers are looking at their calendars with a degree of trepidation. A date is circled: Dec. 14th. And below it says: "Wake up at 4 AM for the Geminid meteor shower."
"It's going to be cold," says Bill Cooke of NASA's Meteoroid Environment Office. "But that is the best time to see the 2013 Geminid meteor shower."
Geminids appear every year in mid-December when Earth passed through a stream of debris from "rock comet" 3200 Phaethon. Typically more than 100 meteors per hour stream out of the radiant in the constellation Gemini.when the shower peaks on Dec. 13th and 14th.
There is a problem, however. This year a nearly full Moon will reduce the number of visible meteors 2 to 3 fold. Most of the shower's peak will suffer from lunar glare. Most, but not all.
"There is a 'magic hour' of good visibility just before dawn on Saturday the 14th," says Cooke. "The moon sets around 4 AM. The dark time between 4 AM and sunrise is a great time for meteor watching."
On Friday the 13th, Cooke will host a live web chat about the Geminids. He and colleagues Danielle Moser and Rhiannon Blaauw from the Meteoroid Environment Office will be on hand to answer questions from 11 p.m. until 3 a.m. EST. They will also be broadcasting live images of the sky over the Marshall Space Flight Center. Cooke expects to see dozens of Geminids during the broadcast.
"The Geminid meteor shower is the most intense meteor shower of the year," notes Cooke. "It is rich in fireballs and can be seen from almost any point on Earth. Even a bright moon won't completely spoil the show."
Moreover, the debris stream from rock comet 3200 Phaethon is broad, so the shower is fairly active all the way from Dec. 12th through 16th. "If you miss the magic hour on Saturday morning, try looking on one of the adjacent nights," Cooke urges.
Whichever night you chose, the Geminids are going to be cold. Bundle up and enjoy the show.