Skywatchers are getting set for the Geminid meteor shower, which this year peaks in the late evening of Monday, Dec. 13, and on the following morning.

The Geminids are considered among the year’s best and most reliable meteor showers, according to the National Aeronautics and Space Administration, capable of delivering scores of shooting stars per hour during their peak. But this year, some of the brilliant streaks of light the meteors leave behind when they race across the night sky could be washed out by light from a moon...

Skywatchers are getting set for the Geminid meteor shower, which this year peaks in the late evening of Monday, Dec. 13, and on the following morning.

The Geminids are considered among the year’s best and most reliable meteor showers, according to the National Aeronautics and Space Administration, capable of delivering scores of shooting stars per hour during their peak. But this year, some of the brilliant streaks of light the meteors leave behind when they race across the night sky could be washed out by light from a moon that is 78% full.

And moonlight isn’t the only threat to the dark skies needed for a clear view of the meteors. Clouds can block the view, and light pollution from buildings, streetlights and other sources on the ground can wash out fainter meteors.

“The rise of big cities and stuff has made it more and more difficult to see meteors,” said Bill Cooke, lead astronomer for the Meteoroid Environment Office at NASA’s Marshall Space Flight Center in Huntsville, Ala.

He said increased light pollution means that today’s skywatchers see fewer shooting stars than their counterparts did decades ago. But meteor showers that tend to serve up lots of brightly colored fireballs—including the Geminids and summer’s Perseids—are still worth stargazers’ time, Dr. Cooke said.

“You can still enjoy them even with some light pollution,” he said.

“For members of the general public, there are only two meteor showers worth going out for—the Geminids and the Perseids,” Dr. Cooke said, adding, “When I was younger, the Geminids were one of the few meteor showers I’d go outside and freeze my carcass off for.”

For the best view of the Geminids, Dr. Cooke recommended heading outside after the moon has dropped below the horizon, around 2 a.m. local time. The shower will continue through twilight. Find a dark place away from city lights and with an unobstructed view of the sky. Lie on your back, and look straight up. No need for a telescope or binoculars, as these will limit your view to only a small portion of the sky at a time.

Give your eyes at least 30 minutes to adjust to the darkness. Don’t check your cellphone—its light will disrupt your eyes’ adjustment.

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Geminids can be glimpsed almost all around the globe, though more meteors will be visible to observers in the Northern Hemisphere than to those in the Southern Hemisphere, according to NASA.

The Geminids are named for the Gemini constellation, from which the meteors seem to originate. In reality, the meteors are fast-moving bits of dust and debris left by 3200 Phaethon, a 3.6-mile-wide space rock orbiting the sun whose debris trail intersects with Earth’s orbit each December. When these bits hit the atmosphere, at speeds around 78,000 miles an hour, they burn up and leave streaks in the sky.

Under ideal viewing conditions, an observer of the Geminids might see up to 150 meteors an hour during the shower’s peak, or approximately three a minute. But this number—which astronomers call the zenithal hourly rate—assumes that the skies are perfectly dark and cloudless, and that Gemini is just overhead.

More likely, NASA said, observers will glimpse 30 to 40 Geminids an hour.