The 2011 Geminid meteor shower

Dec 13, 2011 By Dr. Tony Phillips
Credit: Tony Phillips

The 2011 Geminid meteor shower peaks on the night of Dec. 13-14, and despite the glare of a nearly-full Moon, it might be a good show.

"Observers with clear skies could see as many as 40 Geminids per hour," predicts Bill Cooke of the Environment Office.  "Our all-sky network of meteor cameras has captured several early Geminid fireballs.  They were so bright, we could see them despite the moonlight."

The best time to look is between 10 pm local time on Tuesday, Dec. 13, and sunrise on Wednesday, Dec. 14th. Geminids, which spray out of the constellation Gemini, can appear anywhere in the sky. "Dress warmly and look up," says Cooke.  "It's that simple."

This video is not supported by your browser at this time.

The source of the Geminids is near-Earth asteroid 3200 Phaethon. Most meteor showers come from comets, so having an asteroid as a parent makes the Geminids a bit of an oddball.

"This is the thing I love most about Geminids," says Cooke.  "They're so strange."

Every year in mid-December, Earth runs through a trail of dusty debris that litters the orbit of 3200 Phaethon. Comets vaporizing in hot sunlight naturally produce such debris trails, but rocky asteroids like 3200 Phaethon do not. At least they're not supposed to. The incongruity has baffled researchers since 1983 when 3200 Phaethon was discovered by NASA's IRAS satellite.

One clue: 3200 Phaethon travels unusually close to the sun. The asteroid's eccentric orbit brings it well inside the orbit of Mercury every 1.4 years. The rocky body thus receives a regular blast of solar heating that might somehow boil jets of dust into the Geminid debris stream.

In 2009, NASA's STEREO-A spacecraft saw this process at work.  Coronagraphs onboard the solar observatory watched 3200 Phaethon as it was swinging by the sun.  Sure enough, the asteroid doubled in brightness, probably because it was spewing jets of dust.

"The most likely explanation is that Phaethon ejected dust, perhaps in response to a break-down of surface rocks (through thermal fracture and decomposition cracking of hydrated minerals) in the intense heat of the Sun," wrote UCLA planetary scientists David Jewitt and Jing Li, who analyzed the data.

Jewett and Li's "rock comet" hypothesis is compelling, but they point out a problem: The amount of dust 3200 Phaethon ejected during its 2009 sun-encounter added a mere 0.01% to the mass of the Geminid debris stream--not nearly enough to keep the stream replenished over time. Perhaps the rock comet was more active in the past …?

"We just don't know," says Cooke. "Every new thing we learn about the seems to deepen the mystery."

Led by Cooke, the Meteoroid Environment Office has just released an app for iPhones and iPads to help citizen scientists count and report their observations to NASA. The "Meteor Counter" is available for free from Apple's app store: http://itunes.apple.com/us/app/meteor-counter/id466896415

Explore further: Cassini sees sunny seas on Titan

Related Stories

Geminid meteor shower defies explanation

Dec 07, 2010

The Geminid meteor shower, which peaks this year on Dec. 13th and 14th, is the most intense meteor shower of the year. It lasts for days, is rich in fireballs, and can be seen from almost any point on Earth.

Asteroid Shower

Dec 03, 2007

Mark your calendar: The best meteor shower of 2007 peaks on Friday, December 14th.

Geminid meteor shower 2011

Dec 07, 2011

Its the finale of this year’s meteor showers: The Geminids will start appearing on Dec. 7 and should reach peak activity around the 13th and 14th. This shower could put on a display of up to 100+ meteors ...

Geminids meteor shower to be 'lively' show

Dec 09, 2010

Baby, it's cold outside -- but you can still enjoy the best meteor shower of the year. The 2010 Geminid meteor shower promises to be lively, with realistic viewing rates of 50-80 meteors per hour and potential ...

Recommended for you

Cassini sees sunny seas on Titan

13 hours ago

(Phys.org) —As it soared past Saturn's large moon Titan recently, NASA's Cassini spacecraft caught a glimpse of bright sunlight reflecting off hydrocarbon seas.

Is space tourism safe or do civilians risk health effects?

16 hours ago

Several companies are developing spacecraft designed to take ordinary citizens, not astronauts, on short trips into space. "Space tourism" and short periods of weightlessness appear to be safe for most individuals ...

An unmanned rocket exploded. So what?

19 hours ago

Sputnik was launched more than 50 years ago. Since then we have seen missions launched to Mercury, Mars and to all the planets within the solar system. We have sent a dozen men to the moon and many more to ...

NASA image: Sunrise from the International Space Station

20 hours ago

NASA astronaut Reid Wiseman posted this image of a sunrise, captured from the International Space Station, to social media on Oct. 29, 2014. Wiseman wrote, "Not every day is easy. Yesterday was a tough one. ...

Copernicus operations secured until 2021

20 hours ago

In a landmark agreement for Europe's Copernicus programme, the European Commission and ESA have signed an Agreement of over €3 billion to manage and implement the Copernicus 'space component' between 2014 ...

User comments : 4

Adjust slider to filter visible comments by rank

Display comments: newest first

Pirouette
3 / 5 (4) Dec 13, 2011
Hoping there's no cloud cover tonight so we can watch the show.
GSwift7
3 / 5 (2) Dec 13, 2011
I hope I have good seeing conditions tonight. I love a good meteor shower.
Cave_Man
3 / 5 (2) Dec 13, 2011
Oh man I hope tonight the sky clears up, im about to start on my igloo and I could put a huge plexiglass skylight in the top for some really comfortable meteor shower viewing, I just have to figure out where the constellation gemini is.
Pirouette
2.3 / 5 (3) Dec 13, 2011
Cave_Man. . .look at the skymap in the article. When you go outside tonight, look to the East and locate Orion's Belt, then go across to your left to the Gemini and a little left of that is where the Geminid shower will show up Good hunting.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.