Crank your necks skywards, stargazers. The next celestial show is for you.
Night owls adventurous enough to brave the cold can catch the Geminids meteor shower, which is supposedly the most intense meteor shower of the year. It peaks late Friday night into early Saturday morning.
"It's like seeing the Grand Canyon," said Steven Spangler, a University of Iowa physics and astronomy professor. "It's one of the wonders of nature.
"Then to think these are pieces off an asteroid, it only adds to the spectacle."
You should be able to see a sneak preview Thursday night, and some level of showers will be visible for the next four or five nights. For professional and amateur astronomy buffs, this is one of the big events of the year.
To see Geminids, drive outside the city away from light pollution, Spangler advised. The Eastern Iowa Observatory and Learning Center at Palisades-Dows Preserve outside Ely is a popular place amateur astronomers go for meteor-shower watching.
Observatory director John Leeson said he won't decide until Friday afternoon whether to open the center, which would offer a chance to warm up. Open or closed, people can still come out for good views late Friday night into early Saturday, he said.
You'll want to bundle up, though. The forecast for overnight Friday is 17 degrees and some clouds.
"What makes meteor showers of such general interest is the unpredictability," said Leeson, who is also a member of the Cedar Amateur Astronomers. "You could, and often do, see that fireball or bright meteor that is pretty much worth talking about the next day. But only those willing to spend a few hours in the dark and cold are rewarded like that."
The moon is waxing gibbous, or a few days from full. The bright reflection could obstruct views during ideal hours for watching the Geminids between midnight and dawn, when more than 100 meteors an hour will be streaking across the sky. But watchers still should be able to see some meteors, Spangler said.
The truly dedicated can get prime viewing in the predawn hours after the moon sets on early Saturday morning, between 4 and 5 a.m.
Geminids earned its name because the meteors all appear to radiate from the constellation Gemini — although they don't actually, Spangler said.
When people talk about seeing shooting stars, those are actually meteors, such as the Geminids entering the Earth's atmosphere. Both Earth and Geminids are orbiting the sun, and once a year those orbits align.
When a meteor enters Earth's atmosphere, it burns up from the friction, which creates the shooting light that lasts for a split second, explained Bill Cooke, a NASA meteoroid expert who spoke on a conference call with reporters on Thursday from NASA's Marshall Space Flight Center, Huntsville, Ala.
Geminids, which is an active meteor shower from Dec. 4 to Dec. 16, is unique from the several other meteor showers throughout the year because it travels closer to the sun, which makes the shower more intense, Cooke said.
It is also different because most meteor showers come from comets, which produce meteors of ice, while Geminids have broken off an asteroid, which are more like pieces of rock.
The asteroid, 3200 Phaethon, was discovered in 1983, but the Geminids meteor shower has been active for around 200 years.
NASA's Cooke said it's grown stronger over time. When it was first spotted, it yielded about 20 meteors an hour, while in its next 10 years it could exceed 200 meteors an hour, Cooke said.
This is Jupiter's gravity tugging the stream of debris that comprise the Geminids ever closer to Earth as time goes on.
But, while it is possible for meteors to reach Earth, we are not in danger, he said. The meteors burn up 30 or 40 miles above our heads.
"Technically they are striking Earth," Cooke said. "If it weren't for the atmosphere, they would plow into the ground."You can watch the Geminids with very little fear of being whacked on the head."