The peak of the Geminid meteor shower is set to make for a spectacular view of the cosmos this month.
December’s robust Geminids are known to throw as many as 120 bright meteors per hour and can be viewed during the evening hours as well as predawn. Astronomers expect the most meteors to be visible Tuesday night through Thursday.
“This is it, the shower we’ve all been waiting for,” astronomer Bob King said in his Dec. 11 column for Sky and Telescope. “Not only is it the year’s most prolific shower, the moon is essentially out of the picture.”
In 2016, the luminous glow of a full moon obscured the zippy Geminids, but this year the moon is in its crescent phase, a slender slice of light in the sky that shouldn’t interrupt the show.
The Geminids are unique not just in quantity but also birthplace. Most meteor showers come from comets, roiling cauldrons of gas, dust, ice and rock that have glowing heads and tails. According to NASA, Geminids appear as the Earth crosses the path of an inactive chunk of rock in space that doesn’t shed debris. The rock has been named 3200 Phaethon.
“Phaethon’s nature is debated,” NASA astronomer Bill Cooke said. “It’s either a near-Earth asteroid or an extinct comet, sometimes called a rock comet.”
The Geminids are Cooke’s favorite “because they defy explanation.”
King cautions that the estimate of 120 meteors per hour is an idealized number, visible only under perfect conditions in rural areas.
“Depending on the time you observe and local light pollution, counts will vary,” King said. “At my observing site, which is handicapped by minor to moderate sky glow, I cut the rate in half to keep expectations realistic. A meteor a minute is certainly nothing to complain about.”
The Geminids are the namesake of the Gemini constellation, from which they appear to radiate. The shower can be viewed with the naked eye over clear, dark skies across most of the world.
As long as stargazers are away from bright lights and look up in any direction, they should be able to see the shower, according to NASA. The shower peaks just after 9 p.m. Dec. 13 and lasts until dawn Dec. 14.
“When you see a meteor, try to trace it backwards,” Cooke said. “If you end up in the constellation Gemini, there's a good chance you've seen a Geminid.”
NASA will broadcast the Geminid shower live on Ustream Dec. 13 from the Automated Lunar and Meteor Observatory at NASA’s Marshall Space Flight Center in Huntsville, Alabama.