The Northern Hemisphere will get an additional show of glittering lights this holiday season as a major annual meteor shower peaks during the weekend, bookending a year of magical celestial happenings that included a total solar eclipse and visits from the Northern Lights.
As many as 120 meteors can be seen per hour under perfect viewing conditions every year around mid-December. Named the Geminids after the constellation Gemini, from which they appear to radiate, these bright yellow "shooting stars" can travel up to 22 miles per second -- making it one of the slower meteor showers.
However, a near-full moon will coincide with their peak this year, offering enthusiastic stargazers a less-than-ideal view, said Joe Guzman, a local astronomer and public educator. "A bright moon, city lights, maybe fog, particulates in the air, they all conspire against us," he said.
But from Friday night to Saturday morning, "the brighter streaks will punch through the glare."
"The great thing about the Geminids is that the mosquitoes are gone, unlike the Perseids or the Leonids in the summertime," he said. "So take a nap and get up, because the peak is around 2 a.m. That's when the constellation Gemini is the highest above the horizon."
However, the meteors might be visible earlier in the evening, starting an hour after sunset.
"If you're diligent, and if you bundle up, look to the east, and Gemini will be rising," Guzman said. "And they can appear anywhere in the sky, to the north, to the west, anywhere. So don't just look to the east."
According to NASA, the Geminids began appearing in the mid-1800s. But it was only in 1983 that it was discovered they originated from an asteroid -- instead of a comet as most meteor showers do -- that takes 1.4 years to orbit the sun.
"The orbit of this asteroid coincided with the regular annual appearance of the Geminids. They put two and two together, and bang!" Guzman said.
The asteroid approaches the burning star so closely that it was named 3200 Phaethon, after the Greek mythology character who drove the chariot for the sun god Helios. Bits of the asteroid come loose as it loops around, which Earth passes through in its orbit. When the debris collides with the atmosphere it disintegrates in fiery, colorful streaks.
"For this particular meteor shower, you're going to have some company in the sky," Guzman said.
Look for Venus in the south to southwestern skies. The brightest planet will be at its most brilliant level this time of year, according to the Adler Planetarium. Mars and Jupiter will also be visible as they rise in the east-northeast.
Another annual meteor show will also overlap with the Geminids this time around; It's minor and not as vibrant, with five to 10 meteors per hour. Called the Ursids, they appear to come from the Ursa Minor constellation, colloquially known as the Little Dipper.
"So you may have meteors all over the sky," he said.
As they coincide, these celestial objects will put on a rare show that Guzman said can be a grounding and humbling experience.
"Just enjoy being part of the universe. All these elements in our bodies, we're watching them streak across the sky," he said.
It's something he tries to instill in his young astronomy students: "The nitrogen, the oxygen, the carbon all came from the hearts of stars that blew up millions of years ago. We don't even know these stars anymore, but the universe has a way of recycling all these elements. And we are now those stars, and what we're doing is we're looking back home. We're looking back (to) where we came from."
After midnight: The best time to catch the meteor shower is between midnight and dawn, though they might be slightly visible an hour after sunset and brighter anytime after 8 p.m.
"People are under the misconception that you can't see anything in the city," Guzman said. "That's not the case. Granted, a darker environment is much preferred, we all agree on that. But there is a host of things that you can enjoy and observe within the city limits, and that includes the Geminids and other meteor showers."
According to the Adler Planetarium, finding a way to block light from the moon may improve visibility.
With the naked eye: The planetarium recommends not using telescopes since the location of the meteors can be unpredictable as they move fast. Viewers can let their eyes adjust to the darkness for around half an hour to see the Geminids more clearly.
"We are fortunate here in the city to have the lake directly to our east, and celestial objects rise in the east. So we get the advantage of having a dark sky in that direction," Guzman said.
He suggested finding the Gemini constellation as it rises -- it'll be on the left side of the more recognizable Orion constellation, named after the hunter in Greek mythology and wearing three stars for a belt.
Find darkness: For Chicagoans who can't leave the city, heading toward the lakefront and looking beyond the horizon might offer a relatively dark view. Those who can drive to avoid pollution from city lights might want to head west of Aurora and Elgin, south of Joliet and north of Waukegan to avoid the brightest lights. Maps like lightpollutionmap.info indicate the best viewing locations.
In Illinois, the International DarkSky Association also recommends heading to these communities and parks for dark skies and prime viewing: the village of Hawthorn Woods, Homer Glen, the Middle Fork River Forest Preserve near Urbana-Champaign and Mount Forest Island in the Palos Preserves.
At 5:30 a.m., the night sky and stars will begin to fade from view as dawn approaches at 6:39 a.m. and the sun rises over the city at 7:10 a.m.
Look for clear skies: Clouds can present another pesky obstacle to catching a glimpse of the meteor shower. According to a National Weather Service forecast, 70% to 80% of the sky above the Chicago area will have clouds between midnight and 3 a.m. Saturday.