While there have been many opportunities to watch meteor showers in 2015, including the Perseids in August and the Leonids in November, the king of the meteor showers has officially arrived.
Visible from Dec. 4-16, the Geminids meteor shower will reach peak visibility during the night of Sunday, Dec. 13 into the pre-dawn hours of Monday, Dec. 14, streaking as many as 120 multicolored fireballs per hour across the skies of the Northern and Southern Hemispheres, according to NASA. Combined with a waxing, early setting crescent moon and the crisp air of December, Chicago-area viewing conditions could be ideal–pending weather conditions–for this year’s prolific, fireworks-like display.
“About an hour or two after the sun sets in the west, the thin crescent moon sets,” said Adler Planetarium master educator Michelle Nichols. “So if you’re going out at 10 o’clock at night local time, the Geminids will start popping up in the sky and there will be no moon to compete with this year to wash out those dimmer meteors—we just have our light pollution to compete with. That doesn’t happen every year. Sometimes we have a big, bright, full moon to worry about.”
Even if you remove the moon from this viewing equation, light pollution can still make it a challenge to fully observe meteors in urban environments and the suburbs. Whereas visibility can also depend on the brightness of the meteor itself, the key to unobstructed viewing is watching from a dark, open-sky location—preferably rural—that is away from city lights.
“There’s no one particular direction to look. These things range over such a large area of the sky, there’s always a chance you’ll see something.”
During the early hours of the shower (around 10 p.m.), look for slow "Earth-grazer" meteors traveling horizontally across the Earth’s atmosphere. These long-lasting meteors will make way for brighter meteors overhead as the shower intensifies into the wee hours of the morning.
“Basically for any meteor shower, the really good time is always going to be after midnight. It just helps that you can start to see the Geminids earlier,” Nichols said. “So, 2 or 3 o’clock in the morning is ideal for going out. Even if you wanted to get up at 5 a.m., you may still start to see them, although you’ll see fewer of them as you get closer to sunrise. But it’s still worth a try.”
3200 Phaethon and the origins of the Geminids
A meteor shower occurs when the Earth runs into the trail of debris in space that is left by a passing comet.
Here’s how it works: Comets heat up as their orbit moves them closer to the sun and as a result, they lose some of their ice and dust. This essentially creates debris. If the Earth encounters such a trail of debris in its atmosphere, it results in a meteor shower.
“Just like when people put their hands together and rub them real fast—you feel heat—which is caused by friction,” Nichols explained. “So this material is traveling at literally tens of thousands of miles per hour and it heats up really quickly, and as it burns up, it causes the air around it to glow. Because we’re talking about stuff that’s on the order of a grain of salt in size, you’re not actually seeing the thing itself burn, you’re seeing the glowing, super-heated air around it, which we see as quick streaks of light in the sky.”
A unique characteristic of the Geminids meteor shower is that it appears to originate from 3200 Phaethon, a mysterious object often classified as a rocky asteroid, rather than an icy comet.
“Phaethon probably was a comet that left its trail of stuff while it was a comet, but what’s left now seems to be an asteroid—it’s just lost all its ices,” said Nichols. “Phaethon probably used to have a lot more ice, but as the comets orbit the sun, they’re going to lose more and more of that material over a long period of time. Almost all of the other meteor showers that we know of—where we know the object that creates the meteor shower—they’re almost all comets. But even those objects, given thousands, hundreds of thousands, millions of years, are going to lose more and more ice until they will become extinct comets as well.”
Meteor showers are typically named after the constellation that they appear to be falling away from in the sky (this is also known as the radiant point). In the case of the Geminids, as its name suggests, the meteors appear to be originating from the direction of the stars in the constellation Gemini. Nichols explained that it’s all a matter of perspective and there’s no need to locate Gemini in the sky in order to observe the Geminids.
“You don’t have to worry about being in a specific location,” Nichols said. “I generally tell people to go outside, face east, and look up above your head. If that’s the only sky patch you have available, great—use it. If you can see the whole sky down to the horizon, great—use it. There’s no one particular direction to look, because these things range over such a large area of the sky, there’s always a chance that you’ll see something.”
Rely on your eyes
Telescopes and other magnification devices can be as much of an obstruction to viewing meteors as light pollution.
“I get a lot of questions about people asking, ‘So, do I need a telescope to see a meteor shower, or binoculars?’" Nichols said. "I say, 'Nothing. You need a chair that you can sit back in comfortably and watch the sky.' If you’re using a pair of binoculars or a telescope—the more magnification you’ve got, the smaller the piece of sky is that you are looking at. So, put all of that stuff away."
With an average of 60 to 70 meteors per hour and roughly one or two sightings per minute during its peak, the Geminids offers the most abundant, reliable meteor show of the year. Considering that the event lasts almost two weeks, there's no reason to wait until the 13th to go outside and start looking.
“It’s best to go out in the evening of the 13th into the 14th, but if you want to give it a try a few days ahead of time, a few days after, that’s okay too,” Nichols said. “It’s definitely not uncommon to see meteors outside of that peak date, so you may very well get a couple of bright ones on the 12th or 14th that you wouldn’t have seen on the 13th, it’s just that you’ll have many fewer per hour seen outside of those peak times. Even if you can’t get out of the city, get outside, bundle up, look up, get some hot cocoa, grab a chaise lounge, and just enjoy the sky for a while.”
Watch the Geminids meteor shower online
Unfortunately, the Chicago area forecast is calling for cloudy skies and rain this weekend. In the event of inclement weather, Slooh will be broadcasting a live stream of the Geminids meteor shower online beginning at 7 p.m. CST Sunday, Dec. 13, that you can watch here.
NASA will also be broadcasting a live stream on Dec. 13 from 10 p.m.-3 a.m. CST that you can watch here.
Watch a video about the Geminids meteor shower, produced by NASA, below:
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