The cosmos ignites the grand finale of celestial fireworks this week with the peak of the Geminids meteor shower.
Stargazers eagerly anticipate December’s robust Geminids, which are known to throw as many as 120 bright meteors per hour and can be viewed during the evening as well as pre-dawn. Astronomers expect the most meteors to be visible Tuesday night through Thursday.
“This is it, the shower we’ve all been waiting for,” said astronomer Bob King in his 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 phase is waning crescent, a slender slice of light in the sky that shouldn’t interrupt the annual 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 that spit out debris. But the Geminids appear as the Earth crosses the path of an asteroid, which is an inactive chunk of rock in space that doesn’t shed.
NASA astronomer Bill Cooke has said that the Geminids are his favorite meteor shower not because they are bright and robust, but because they “defy explanation.”
Because the asteroid 3200 Phaethon — which creates the Geminids — is a bit of a mystery, it has been dubbed a “rock comet” by some scientists.
King cautions that the 120-meteors-per-hour estimate 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, where they appear to radiate from. But they can be viewed in all areas of the night sky.
While the meteors can be visible after 9 p.m., they are most plentiful between midnight and 2 a.m. as the constellation climbs higher in the sky, according to the online astronomy website Earth and Sky.