Lake County News | California

Mar 31st
Text size
  • Increase font size
  • Default font size
  • Decrease font size

Home News Latest Space News: Geminid meteor shower peaks this week

Space News: Geminid meteor shower peaks this week

E-mail Print PDF

Every year in mid-December, astronomers look up in the sky and witness a mystery.

It announces itself with a flurry of shooting stars. For several nights in a row, dozens to hundreds of meteors per hour cut across the glistening constellations of winter, each one a little puzzle waiting to be solved.

“It’s the Geminid meteor shower – set to peak on Dec. 13 and 14,” said Bill Cooke of NASA’s Meteoroid Environment Office. “Although the Geminids come every year, we still don’t fully understand them.”

Most meteor showers are caused by icy comets, which spew jets of meteoroids when they are heated by sunlight. The Geminids are different. The parent is not a comet but a weird rocky object named 3200 Phaethon.

When 3200 Phaethon was discovered in 1983 by NASA’s IRAS satellite, astronomers quickly realized that they had found the source of the Geminids.

The orbit of 3200 Phaethon was such a close match to that of the Geminid debris stream, no other conclusion was possible. Yet here was a puzzler: Everything about 3200 Phaethon suggests it is an asteroid.

In fact, 3200 Phaethon resembles main belt asteroid Pallas so much, it could well be a 5-kilometer chip off that 544 km block.

“If 3200 Phaethon broke apart from asteroid Pallas, as some researchers believe, then Geminid meteoroids might be debris from the breakup,” speculated Cooke.

There is, however, another possibility: Perhaps 3200 Phaethon is a “rock comet.”

A “rock comet” is a new kind of object being discussed by some astronomers. It is, essentially, an asteroid that comes very close to the sun – so close that solar heating scorches dusty debris right off its rocky surface.

Rock comets could thus grow comet-like tails made of gravely debris that produce meteor showers on Earth.

Could this be the answer?

To test the idea, researchers turned to NASA’s twin STEREO spacecraft, which are designed to study solar activity.

In June 2009, STEREO watched 3200 Phaethon passing only 15 solar diameters from the sun’s surface. What happened next surprised UCLA planetary scientists David Jewitt and Jing Li, who analyzed the data.

They said 3200 Phaethon unexpectedly brightened by a factor of two. “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.”

So, according to the STEREO observations, 3200 Phaethon does behave like a rock comet.

The “rock comet” hypothesis is compelling, but Jewett and Li point out a problem: The amount of dust 3200 Phaethon ejected during its sun-encounter added a paltry 0.01 percent to the mass of the Geminid debris stream, not enough to keep the debris stream stocked up with meteoroids for the annual display of shooting stars.  3200 Phaethon is not spewing enough dust to account for the Geminids.

Could the rock comet have been more active in the past?

“We just don’t know,” said Cooke.

Forecasters expect Geminid meteor rates to top 100 per hour when the shower peaks on the moonless nights of Dec. 13 and 14. Cooke encouraged sky watchers to go out, look up and savor the mystery.

Dr. Tony Phillips works for the National Aeronautics and Space Administration.

Subscribe to me on YouTube
Comments (2)Add Comment
written by Vogel, December 10, 2012
What the heck are you smoking??? Your reply has nothing to do with the article. Time to go for another hit of meth.
Just wondering...
written by ca215, December 10, 2012
...whether or not Dr Tony Phillips would rather see ALL the words making up the article about Geminid meteor showers, or instead have some of the words covered by ads for several businesses operating in Lake County.

I know, every square inch of ads onscreen sells for a large amount of $$$$.

Here's the thing: if I want info about a lawyer, where to possibly buy a car, where to begin looking for a realtor, etc., I can run Search "Lake County CA attorneys" with this computer and, of course, removing the quotation marks before hitting "enter."

Or: there's a thing called a telephone book where I may find listings for businesses. Whatever corp sets up the items included in that book manages to do such setting-up without cutting off portions of the contact phone numbers or addresses OF such businesses.

It seems the news column inches could be made slightly narrower and, if that happened, there would be more than enough room to splash the ads beside --- not over --- the articles' written material.

Write comment
You must be logged in to post a comment. Please register if you do not have an account yet.