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.

8 Responses

  1. MBZ

    Hey Bob,
    Glad you saw the little fella. I never even made it outside due to an acute bout of “life-is-what-happens-to-you-while-you’re-busy-making-other-plans” syndrome.
    Quick question. I did get to fetch ephemeris, but didn’t see any function to create a detailed map. Granted, my mission was rushed, then interrupted, then totally aborted… Before I go digging, is this map function possible at JPL Horizons?
    Might be able to give Toutatis a try, maybe.

    ???“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.”???

    1. astrobob

      Hi MBZ,
      I see what you mean. What I wrote could be taken to mean JPL provides maps. They don’t. You’ll need to plot the coordinates given on your own star atlas. If you have a star-charting program that allows you to input your own orbital elements for Toutatis, that’s even better.

      1. MBZ

        That’s what I figured. Would have been far too cool a function to be for real.
        Haven’t a star charting program yet. It’s only been a a short while since I returned to this hobby. But I’ve got good paper charts, old relic that I am. Better make the leap to computer star charts before I get even further behinder 😉
        Looking forward to Thursday night! You stay warm and have fun, and as usual… Thanks a million.

        1. astrobob

          I’ve had trouble getting accurate paths of newly discovered, fast-moving asteroids with MegaStar, which otherwise works perfectly with comets and named asteroids. That’s why I’ve gone to hand-plotting fast, new asteroids using JPL ephemerides. Works all the time. Let us know how it goes Thursday night. I’ll be out if it clears.

          1. Richard Keen

            Bob, I use “Project Pluto” Guide v8.0, which works real well with those Earth-grazing asteroids. However, all, or most, of these map plotting programs perform only two-body predictions, i.e., the asteroid’s path around the Sun with no influence from Earth’s gravity. The JPL Horizons program includes the Earth’s effect, so is much more accurate.
            But there’s a trick – I go to the JPL Horizons to calculate the orbital elements at the time of closest approach, so the Earth’s effect is included in the elements. Then plug those elements into Guide, and voila! A track that’s dead on around close approach!

          2. astrobob

            Guide’s a good program. I’ve also plugged in the latest elements from the JPL page into Megastar, but the tracks are often just enough off to cause frustration. I have Guide but haven’t used it in a while – I’ll give it a try when the next Earth-approacher arrives.

  2. larsa

    Hi everyone!

    I was just watching from a clear flawless sky in Northeast TX and I saw some beautiful meteors tonite! Some a pretty blue and a bright one almost a white-yellow color! I am seeing a ton just to the north and Im having the most luck seeing them between Venus and the Ursa Major =D I did see quite a few to the northeast too. I hope everyone who wanted to see them got to go outside!!

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