Geminid Meteor Shower! from a EarthSky post by Bruce McClure

December 08, 2014  •  Leave a Comment

The peak night of the 2014 Geminid meteor shower will probably occur on the night of December 13 (morning of December 14). The night before (December 12-13) may offer a decent sprinkling of meteors as well. Geminid meteors tend to be few and far between at early evening, but intensify in number as evening deepens into late night. A last quarter moon will rise around midnight, but Geminid meteors are bright! This shower favors Earth’s Northern Hemisphere, but it’s visible from the Southern Hemisphere, too. If you’re at a temperate latitude in the Southern Hemisphere, try waiting a little later – until close to midnight – to see the beginning of the Geminid shower.

Moonlight a factor in Geminid shower in 2014. The December Geminids are a particularly reliable and prolific shower, one of the finest of the year. In a year when moonlight doesn’t obscure the viewing, you can easily see 50 or more meteors per hour on the peak night of the Geminid shower. However, the waning moon might somewhat dampen this year’s display in the peak viewing hours, which is centered at about 2 a.m. local time, no matter where you are on the globe.

Don’t let the moonlight discourage you. A good percentage of these yellow-colored Geminid meteors are quite bright, and may well overcome the moonlit skies.

Of course, you can always watch this shower during the evening hours before moonrise. The moon will rise quite late on December 13 and 14, creating a window of darkness for watching the Geminid shower in the evening. Keep in mind that the moon will rise about an hour earlier on December 13 than it will on December 14.

Even as the moon rises, however, it will be sitting low in the east. If possible, find a hedgerow of trees, a barn or some such thing to block out the moon. Sit in a moon shadow but at the same time, find an expansive view of sky. Or simply look away from the moon. The key to watching meteors is to find an open sky, away from pesky artificial lights. Lie down in comfort, perhaps snuggled up in a warm sleeping bag, and look upward.

The Geminid meteors radiate from near star Castor in Gemini.

Why are these meteors called the Geminids? If you trace the paths of the Geminid meteors backward, they all seem to radiate from the constellation Gemini, hence the reason for the meteor shower’s name.

In fact, the radiant point of this meteor shower nearly coincides with the bright star Castor. However, the radiant point and the star Castor just happen to be a chance alignment, as Castor lies about 52 light-years away while these meteors burn up in the upper atmosphere, some 100 kilometers (60 miles) above the Earth’s surface.

You don’t need to find the constellation Gemini to watch the Geminid meteor shower. These medium-speed meteors streak the nighttime in many different directions and in front of numerous age-old constellations. It’s even possible to see a Geminid meteor when looking directly away from the shower’s radiant point. However, if you trace the path of any Geminid meteor backward, it’ll lead you back to the constellation Gemini the Twins.

Painting of 1860 earthgrazer fireball by Frederic Edwin Church. Image credit: Wikimedia Commons

Painting of 1860 earthgrazer fireball by Frederic Edwin Church. Image credit: Wikimedia Commons


An earthgrazer meteor possible at early evening. You won’t see as many Geminid meteors when the constellation Gemini still sits close to the eastern horizon. Even so, the early evening hours present an opportune time to try to catch an earthgrazer meteor.

Earthgrazers are rarely seen but prove to be especially memorable, if you should be lucky enough to catch one. An earthgrazer is a slow-moving, long-lasting meteor that travels horizontally across the sky. As the constellation Gemini, the radiant point of the Geminid meteors, climbs upward throughout the evening hours, the meteors will cross the sky less horizontally and will rain down from a point that’s higher in the sky.

Once Gemini make their appearance, they’ll be out for rest of the night. The Gemini stars Castor and Pollux reach their highest point for the night around 2 a.m. local time. As a general rule, the higher the constellation Gemini climbs into your sky, the more Geminid meteors that you’re likely to see.

Orbit of Asteroid 3200 Phaethon, parent of the Geminid meteor shower

The orbital path of asteroid 3200 Phaethon, and the four inner planets of the solar system: Mercurio (Mercury), Venere (Venus), Terra (Earth) and Marte (Mars). Image credit: Wikimedia Commons

What causes the Geminid meteor shower? Every year, in December, our planet Earth crosses the orbital path of asteroid 3200 Phaethon, a mysterious body that is sometimes referred to as a rock comet.

In periods of 1.43 years, this small 5-kilometer (3-mile) wide asteroid-type object swings extremely close to the sun (to within one-third of Mercury’s distance), at which juncture intense thermal fracturing causes this rocky body to crack and crumble, and to shed rubble into its orbital stream. Annually, at this time of year, the debris from 3200 Phaethon crashes into Earth’s upper atmosphere at some 130,000 kilometers (80,000 miles) per hour, to vaporize as colorful Geminid meteors.

How to watch the Geminid meteors. Why not give the Geminid meteor shower a try? You need no special equipment – just an open view of sky away from pesky artificial lights. Sprawl back in a hammock or a pile of hay, and look upward to witness one of the finest sky attractions of the year: the Geminid meteor shower!

Be sure to give yourself at least an hour of observing time. It takes about 20 minutes for your eyes to adapt to the dark, and moreover, meteors often come in spurts which are interspersed by lulls.

Bottom line: Despite the drenching moonlight in 2014, the reliable Geminid shower is sure to add to the holiday lighting on the nights of December 12-13 and 13-14!


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