Friday, December 6, 2013

Geminid meteor shower 2013--mid December

"Everything you need to know: Geminid meteor shower"


Bruce McClure

December 5th, 2013


The 2013 Geminid meteor shower is expected to peak on the night of December 13-14, though the night before (December 12-13) should offer a decent sprinkling of meteors as well. The sky attraction starts at mid-to-late evening and ends at dawn. The meteors tend to be few and far between at early evening, but intensify in number as evening deepens into late night. No matter where you live worldwide, look for these meteors to fall most abundantly in the wee hours after midnight, centered on 2 a.m. local time.

Although the Geminid shower favors the Northern Hemisphere, it’s visible from the Southern Hemisphere as well. The Geminids start streaking the sky by mid-evening in the Northern Hemisphere, but people at temperate latitudes in the Southern Hemisphere may have to wait until late evening, or close to midnight, to see the beginning of the Geminid shower. Follow the links below to learn more about the Geminid meteor shower in 2013.

Moonlight a major factor in Geminid shower in 2013. 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 bright waxing gibbous moon in 2013 is sure to dampen this year’s display.

But 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 work around the moon. The moon will set before dawn on December 13 and 14, creating a window of darkness for watching the Geminid shower between moonset and dawn. Keep in mind that the moon will set about an hour earlier on December 13 than it will on December 14. Click here for custom sunrise/set calendar. Check boxes for moonrise/set times..

Before the moon sets, however, the moon will be sitting low in the west. 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.

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.

How to find Gemini, the radiant point of the Geminid shower. It’ll be especially easy to find this constellation in December 2013, should you want to see it. That’s because the dazzling planet Jupiter, the fourth brightest celestial body in all the heavens, beams right in front of Gemini.

Jupiter and the constellation Gemini climb into the east-northeast sky by early-to-mid-evening in December 2013.

Have you been watching the blazing planet Venus, the sky’s brightest planet, in the southwest sky after sunset? If so, let Venus give you some idea as to when Jupiter and the constellation Gemini will enter into the starry sky. As Venus sets in the southeast at evening, look for Jupiter and the Gemini stars, Castor and Pollux, to rise over the horizon in the opposite direction. Click here for recommended sky almanacs. They can help you find when Venus sets and Jupiter rises into your sky.

An earthgrazer meteor possible at early evening. You won’t see many Geminid meteors when Jupiter and the constellation Gemini first enter the evening sky, and loom 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 Jupiter and Gemini make their appearance, they’ll be out for rest of the night. Jupiter and 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.

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 2013, the reliable Geminid shower is sure to add to the holiday lighting on the nights of December 12-13 and 13-14! This post contains information about the shower’s radiant point, and tips on when and how to watch December’s Geminid meteor shower.

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