Geminids: How Low Do They Go?

The Marshall Meteoroid Environment office put together the plot below showing the distribution of end heights of Geminids seen with our fireball camera network. 85% of Geminids burn up 40 to 55 miles above Earth’s surface and 15% get below 40 miles altitude.
 
Geminids penetrate deeper into the atmosphere than the Perseids because they are moving slower (78,000 mph for the Geminids compared to 130,000 mph for the Perseids) and are made up of denser material, owing to the fact that the Geminid parent body is rocky asteroid 3200 Phaethon and the Perseid parent is a comet yielding more fragile material.
 

This video shows meteors captured by a wide-field camera at the NASA Marshall Space Flight Center on the night of December 12. There are 141 events; at least 77 of these are Geminids, based on their angular speed and direction of travel. Near the end of the movie, a couple of satellites are visible crossing the field of view.

For those of us sky watching for meteors , this means we have a good chance of viewing a Geminid meteor. Tonight, December 13, into the early morning of December 14 is the peak. Happy meteor watching!

Geminid Over Las Cruces

Hazy skies did little to dim the brightness of this Gemind meteor, which graced the skies over southern New Mexico on the night of Dec. 14 around 7:28 p.m. MST. Moving at 80,000 mph, the 3/4 inch meteor — a piece of the asteroid 3200 Phaethon — flared brighter than the planet Venus before burning up 47 miles above the U.S./Mexico border.

Image credit: Marshall Space Flight Center, Meteoroid Environments Office, Bill Cooke

596 Scheila: An Identity Crisis?


Things are getting a little stranger in the asteroid belt these days! Objects in this zone of the solar system are known to be rocky bodies, though in the past few years several of these bodies have had cometary features detected. One such body is 596 Scheila, which has always been confidently called a main-belt asteroid, meaning it is a rocky body orbiting nicely between Mars and Jupiter causing no trouble to Earth.

Scheila is 113 km in diameter and was discovered in 1906 by August Kopff in Heidelberg and named after an acquaintance of the discoverer. For the past 104 years Scheila has been pleasantly orbiting without much fuss until last week the Catelina Sky Survey found a coma around the object with a 0.68 meter Schmidt telescope; quickly confirmed by many other observers.Scheila, along with several other bodies in the past few years, have created a new class of solar system objects: main-belt comets. Main-belt comets have the orbital characteristics of main-belt asteroids, but exhibit an outgassing, comae, or a dust-tail that is normally seen on icy comets that came from the outer-reaches of our solar system. These bodies are an anomaly and a mystery since an object this close to the sun should have had its ices vaporized away. This has caused another theory to arise that perhaps they are not icy bodies, but perhaps the trail of debris was caused by an asteroid-asteroid collision.

3200 Phaethon, the parent body of the famous Geminid meteor shower, is another example of this. Phaethon was always thought to be an asteroid, a purely rocky body, and even its meteoroids agreed with this, being denser than an average icy-meteoroid. But in recent times Phaethon has exhibited dust-outgassing, causing observers to wonder whether it once was a comet, or if it has had a recently collision to cause the particles.

Unlike Phaethon, Scheila will not intersect Earth’s orbit and thus we will not have a Scheilid meteor shower. Whether this outgassing and dust production from asteroids is due to vaporization of earth or asteroid collisions, only time will tell. Oh, the mysteries of our solar system!


Orbit of 596 Scheila, as computed by the JPL small-body database browser.


Image of 596 Scheila using a V Filter and 10 stacked images of three-minute exposures each.


Image of 596 Scheila using an R Filter and 10 stacked images of three- minute exposures each.

Images were taken via a remote-operated camera located in New Mexico. Stars are trailed because the asteroid was being tracked. You can clearly see the fuzzy “cloud” or coma about the asteroid in the center.
 

Images courtesy of Bill Cooke and Rhiannon Blaauw, NASA’s Meteoroid Environment Office, Marshall Space Flight Center, Huntsville, Ala.

Live Web Chats Today: Geminid Meteor Shower


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 peaks reaching 120 meteors per hour. Anytime between Dec. 12-16 is a valid window for Geminid-watching, but the night of Dec. 13-14 is the anticipated peak.

You have two opportunities to learn more about the Geminids from meteor experts based at NASA’s Marshall Space Flight Center. On Monday, Dec. 13 from 3:00 to 4:00 p.m. EST, meteor experts Danielle Moser and Rhiannon Blaauw will answer your questions, then you can stay “up all night” to observe the Geminids with NASA astronomer Bill Cooke. Have the coffee ready, then join them online from 11:00 p.m. to 5:00 a.m. EST as the Geminids peak in the skies over Earth.

Joining the chats is easy. Simply go to https://www.nasa.gov/connect/chat/geminids2010.html a few minutes before each of the chat start times list above. The chat module will appear at the bottom of this page. After you log in, wait for the chat module to be activated, then ask your questions. Here’s to a spectacular viewing!

False-color composite view of 2008 Geminid meteor shower is courtesy of Bill Cooke, NASA’s Meteoroid Environment Office at the Marshall Space Flight Center.
 

Here Come the Geminids!

Last night the NASA All-sky Meteor cameras detected their first Geminid fireball of 2010!  The fireball, detected from cameras positioned in both Huntsville, Ala., and Chickamauga, Ga., was first spotted over southern Tennessee at a height of 58.7 miles above the ground.  It streaked across the sky over northern Alabama at a speed of 76,300 mph and completely burned up by a height of 53.4 miles.  If the weather remains clear, we should be in for a good Geminid show this year! 


Geminid fireball meteor seen from Huntsville (left) and Chickamauga (right) on December 6, 2010.

Meteor rates should peak early next week, so stay tuned for more news about the Geminid meteor shower!


Image courtesy of Danielle Moser, NASA’s Meteoroid Environment Office, Marshall Space Flight Center, Huntsville, Ala.