Geminid meteor shower: why spectacular light show puzzles scientists

By Pete Spotts, Staff writer / December 13, 2011

Gemenid meteor shower watchers can’t figure out where all the material in the event comes from. Asteroid 3200 Phaethon, the apparent source of the Gemenid meteor shower, doesn’t seem to shed enough rock and dust to account for the shower’s intensity.

The Gemenid meteor shower lights up the sky over the Mexican volcano Popocatepetl. Daniel Aguilar/REUTERS/File

The Geminid meteor shower peaks tonight. Don’t miss it!
Geminid meteor shower gets rave reviews as best of 2010
By now you’ve probably heard that tonight’s the night for what is arguably one of the most spectacular meteor showers of the year, the Geminids.

The shower earns its name from its apparent point of origin, or radiant, in the constellation Gemini.

But where many meteor showers represent Earth’s encounter with dust from a comet, the Geminids appear to have an odd duck of a source: an asteroid that some now call a rock comet.

And it’s not clear from recent observations whether the object, known as 3200 Phaethon, is kicking off enough material to account for the intensity of the meteor shower Earth encounters.

A team of astronomers identified the debris gap in a paper published in the Astronomical Journal in November 2010. And researchers are still puzzling over it.

Although the first recorded observations of the Geminids don’t appear until the early 1860s, modeling studies of the debris’ orbit suggests that the stream is anywhere from 200 to 6,000 years old.

3200 Phaethon was discovered by NASA’s Infrared Astronomical Satellite in 1983. Once scientists determined its orbit, the orbit closely matched with the orbit of the debris stream.

One of the asteroid’s key features is its proximity to the sun at closest approach. It comes nearer the sun than any known asteroid, well inside the orbit of Mercury. This allows surface temperatures to reach 1,400 degrees Fahrenheit.

In their 2010 paper, David Jewitt and Jing Li at the University of California at Los Angeles looked at images from one of a pair of NASA sun-watching satellites taken of 3200 Phaethon during its close approach to the sun. Its brightness increased suddenly, indicating that it was shedding material, just as a comet might.

Given the asteroid’s rocky makeup, the team posited that the object’s relatively quick swing into and out of this hot zone leads to rock fracturing when heated. Comets, on the other hand, shed material when the ices they contain heat and shift directly from solid to gas. In the process, a comet also ejects dust and rock bound up with the ices.

To account for the intensity of the Geminid stream, the duo calculated, the 30-mile-wide 3200 Phaethon would have to repeat the shedding process 10 times per orbit, something no one has observed.

Dr. Jewitt allows in an e-mail exchange that their mass estimate could be off, and that additional outbursts during each orbit could emerge with more-systematic observations.

But for now, the grit gap remains.

So, bundle up, grab a chaise lounge, a Thermos of hot chocolate, and head out to see the show overnight tonight or even Wednesday night. The peak actually is expected to occur at about 2 p.m. Eastern Standard Time Wednesday.

But the shower, which typically produces more than 100 meteors an hour during its peak under dark skies, will be a bit less spectacular than it otherwise might be. Blame the bright, if waning, moon. Moonlight will wash out the dimmer meteor streaks.

Geminid meteor shower: why spectacular light show puzzles scientists – CSMonitor.com.

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Solar Storms Building Toward Peak in 2013, NASA Predicts

by Clara Moskowitz, SPACE.com Assistant Managing Editor
Date: 09 August 2011 Time: 05:06 PM ET

This image from the Solar Dynamics Observatory shows the X6.9 solar flare of Aug. 9, 2011 near the western limb (right edge) of the sun. CREDIT: NASA/SDO/Weather.com

Solar flares like the huge one that erupted on the sun early today (Aug. 9) will only become more common as our sun nears its maximum level of activity in 2013, scientists say.

Tuesday’s flare was the most powerful sun storm since 2006, and was rated an X6.9 on the three-class scale for solar storms (X-Class is strongest, with M-Class in the middle and C-Class being the weakest).

Flares such as this one could become the norm soon, though, as our sun’s 11-year cycle of magnetic activity ramps up, scientists explained. The sun is just coming out of a lull, and scientists expect the next peak of activity in 2013. The current cycle, called Solar Cycle 24, began in 2008.

“We still are on the upswing with this recent burst of activity,” said Phil Chamberlin, a solar scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md., who is a deputy project scientist for the agency’s Solar Dynamics Observatory, a sun-studying satellite that launched in February 2010. “We could definitely in the next year or two see more events like this; there’s a potential to see larger events as well.”

A more active sun

Earth got lucky with the most recent flare, which wasn’t pointed directly at Earth; therefore, it didn’t send the brunt of its charged particles toward us, but out into space. However, we may not be so fortunate in the future, experts warned.

“We’re in the new cycle, it is building and we’ll see events like this one,” said Joe Kunches, a space scientist with the National Oceanic and Atmospheric Administration (NOAA)’s Space Weather Prediction Center. “They’ll be much more commonplace and we’ll get more used to them.”

Spacecraft such as the Solar Dynamics Observatory (SDO), which recorded amazing videos of the Aug. 9 solar flare, and other observatories will be vital in monitoring the sun during its active phase, researchers said.

How sun storms form

Storms brew on the sun when pent-up energy from tangled magnetic field lines is released in the form of light, heat and charged particles. This can create a brightening on the sun called a flare, and is also often accompanied by the release of a cloud of plasma called a coronal mass ejection (CME).

These ejections are the part we Earthlings have to worry about.

As the CME careens through space, it can send a horde of charged particles toward our planet that can damage satellites, endanger astronauts in orbit, and interfere with power systems, communications and other infrastructure on the ground.

“We’re well aware of the difficulties and challenges,” Kunches told SPACE.com. “We know more about the sun than we ever have.”

Can we predict solar storms?

When a big storm occurs, the Space Weather Prediction Center releases a warning to the U.S. Department of Homeland Security, emergency managers and agencies responsible for protecting power grids. Then power grids can distribute power and reduce their loads to protect themselves.

Satellite and power companies are also trying to design technology that can better withstand the higher radiation loads unleashed by solar storms.

Still, scientists would like to offer more advanced warnings when big storms are headed our way.

“We’re being reactive, we’re not being proactive,” Chamberlin said. “We don’t know how to predict these things, which would be nice.”

Chamberlin said solar science has come a long way in recent years, though, and the goal of SDO and other NASA projects is to improve our understanding of the sun and our ability to forecast space weather.

You can follow SPACE.com senior writer Clara Moskowitz on Twitter @ClaraMoskowitz. Follow SPACE.com for the latest in space science and exploration news on Twitter @Spacedotcom and on Facebook.

Solar Storms Building Toward Peak in 2013, NASA Predicts | Solar Flares & Storms | Space & Solar Weather | Space.com.