Take a break from doomsday to enjoy the Geminid meteor shower

The Geminids will appear to radiate from near Castor and Pollux, the two brightest stars in Gemini the Twins. The shower peaks Weds. night – Thurs. morning. Maps made with Stellarium

Doomsday, smoomsday – let’s interrupt this broadcast to talk about the best meteor shower of the year. The Geminids will liven up skies this Thursday night – Friday morning Dec. 13-14 with up to 50 meteors per hour. We’ve all been burned a little by showers that dribble out meteors once every half hour. Not the Geminids. They’re a strong, reliable shower right on par with the August Perseids.

Although occurring at a cold time of year, the shower offers compensation in putting on a decent show during evening hours. You can start watching for meteors around 9  p.m. when Gemini, home to the Geminids, is up in the east. Rates will improve after midnight when the radiant – the point in the sky from which the shower members appear to radiate or travel – climbs high in the southern sky. Hard-core meteor watchers will be out from 2 a.m. until dawn Friday, but casual observers can start around 9 or 10 p.m.

Beautiful Geminid fireball from a few years back. Credit and copyright: Wally Pacholka

With the moon at new phase, expect ideal conditions for viewing. To improve your counts, consider a drive to the country to put the hurt on city light pollution. Real darkness can make a big difference, since there are far more faint meteors than bright.

Most meteor showers originate from debris lost by comets as they orbit the sun. When Earth plows into the stuff, it burns up through friction with our atmosphere, flaring as a meteor or shooting star.

Photos of the Geminid parent asteroid 3200 Phaethon taken over a span of 45 minutes with a 15-inch telescope on Dec. 25, 2010. Dust and rock association with this asteroid is responsible for the Geminids. Credit: Marco Langbroek

The Geminids are different. Instead of comet bits, we’re showered by bits of rock from the asteroid 3200 Phaethon. What likely happened was that sometime in the distant past, the asteroid collided with another, spreading rocky debris along its orbital path. Every year in mid-December, Earth gets peppered by Phaethon dust as we pass through the stream. Geminids are typically travel at modest speeds compared to some showers and appear white to yellow.

If your weather looks cloudy tomorrow night, you’ll still see some Geminids a couple days before and after the Thursday night peak. For best viewing, dress warmly, pack a thermos of your favorite beverage, face east or south and kick back in a chair. I’ve heard hot tubs also make good meteorite viewing stations.

As long as we’re touching on asteroids, last night the sky cleared just enough in my neighborhood to watch asteroid 2012 XE54 creep across the stars of Taurus and Orion during its close pass of Earth. The approximately 120-foot-wide space rock moved in real time like a very slow satellite at 142x through my 15-inch telescope. While the asteroid was exactly on track, it arrived about 3 minutes early of position.

As for 2012 XE54’s predicted eclipse by Earth – yes, it did happen! Others who followed 2012 XE54 measured a steep drop in its brightness to about 17.5 magnitude during the predicted time, much too dim to see in nearly all amateur scopes. It would have been cool to watch it fade from view for an hour, but the sky here in Duluth, Minn. was cloudy then. To see how the asteroid’s light changed during the eclipse, check out the light curve at amateur astronomer Pete Birdwhistle’s site.


Most recent Goldstone radar image of asteroid 4179 Toutatis taken on Dec. 10, 2012. Click picture to see more. Credit: NASA

Toutatis, another Earth-approaching asteroid we looked at a couple days ago, will be making its closest approach tonight around 10 p.m. (CST) at a relatively distant 4.3 million miles.

Radio astronomers will be closely watching the space rock to further refine its orbit, shape and surface features. Amateurs with small telescopes from 4.5 inches on up can spot it traveling slowly among the stars of Cetus the Sea Monster shining at about magnitude 10.8. If you miss tonight, don’t worry. Toutatis will be brighter than 12th magnitude (visible in a 6-inch telescope) all month.

To find Toutatis in your scope, head over to JPL’s Horizons site, select your location and time period, then click the Generate Ephemeris button. That will give you a list of positions for the asteroid you can hand-plot on a detailed star atlas. I’ll try to post a chart for you later today if I can find time.

I’m hoping the Chinese will share closeup photos during the planned flyby of the asteroid tomorrow with their Chang’ e 2 spacecraft. Stay tuned.

UPDATE: Potential second NEW meteor shower is expected Thursday night. Click HERE for more info.

Asteroid 2012 XE54 may be eclipsed during close flyby tonight

The path of 2012 XE54 (in blue) during tonight’s close flyby.  At minimum distance, it will be about 139,500 miles away. Credit: NASA/JPL

Newly-discovered asteroid 2012 XE54 will fly by Earth tonight only 139,500 miles away or slightly more than half the distance to the moon. The rocky body, estimated at between 50-165 feet across (15-50 meters), was discovered only yesterday and will reach minimum distance tomorrow morning around 4:10 a.m. (CST) as it zips through northern Puppis southwest of Sirius. For a few hours before and after that, the asteroid should be visible in 8-inch and larger telescopes at around 13th magnitude. As with all these small bodies, 2012 XE54 will look like a starlight point of light on the move.

When brightest this evening at around 12.9-13.0 magnitude, the asteroid will be cruising through Orion and Monoceros. Positions are shown each hour starting at 9 p.m. CST. Created with Chris Marriott’s SkyMap software

According to Pasquale Tricarico, research scientist at the Planetary Science Institute, there’s a good chance the asteroid will be partially eclipsed by Earth’s shadow between 7:22 – 8 p.m. (CST), an unusual if obscure event. Amateurs and professionals watching at that time might see a drop in the 2012 XE54’s brightness.

It’s not often we get to see an asteroid eclipse. The first known case happened in 2008 when 2008 TC3 passed into Earth’s shadow for an hour before entering the atmosphere, where it shattered and dropped about 10 lbs. of meteorites over Sudanese desert.

Just so we’re clear, we’ve nothing to fear from tonight’s flyby. The asteroid will pass safely by Earth like so many others have in recent years. The map above gives you a general idea of 2012 XE54’s path across the sky. To create your own detailed map to find it in a telescope, click over to the JPL HORIZONS site. There you can set your location and time interval and then plot the asteroid’s positions on a detailed star map. Or you can input its orbital elements into your star-charting program. To see a very cool animation of the possible eclipse, check out Pasquale Tricarico’s website.