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| 3200 Phaethon (blue orbit) will sweep close to Earth on December 16, 2017, just days after the Geminid meteor shower’s peak. Image via Osamu Ajiki (AstroArts)/Ron Baalke (JPL) /Ade Ashford (AN)/AstronomyNow. |
EarthSky.org
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| The Geminids seem to radiate from near the bright star Castor in the constellation Gemini, which lies in the east on December evenings, highest at around 2 a.m. |
Observing around 2 a.m. is best.
This shower favors Earth’s Northern Hemisphere, but it’s visible from the Southern Hemisphere, too.
The Geminids’ parent body – a curious rock comet called 3200 Phaethon – is exceedingly nearby this year, due to make a close sweep past Earth on December 16.
It's likely to be cloudy over the region around North Idaho through the nights the Geminids are most active, December 13-15, and it's going to be cold, but there could be breaks in the clouds, making sightings theoretically possible at least. Those chances diminish as the Geminid showers wane December 16, with a 70-percent chance of snow and freezing rain in Bonners Ferry, conditions are likely to be too overcast and too miserable for meteor watching.
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 the Twins.
This shower’s radiant point nearly coincides with the bright star Castor in Gemini. That’s a chance alignment, of course, as Castor lies about 52 light-years away while these meteors burn up in the upper atmosphere, some 60 miles (100 km) above Earth’s surface.
Again, 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.
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| Watch for the waning moon, Jupiter and Mars around the mornings of the Geminids’ peak in 2017. |
But the greatest number of meteors will fall in the wee hours after midnight, centered around 2 a.m. local time (the time on your clock no matter where you are on Earth), when the radiant point is highest in the sky. As a general rule, the higher the constellation Gemini climbs into your sky, the more Geminid meteors you’re likely to see.
These meteors are often bold, white and bright. On a dark night, you can often catch 50 or more meteors per hour.
You need no special equipment – just a dark, open sky and maybe a sleeping bag to keep warm. Plan to sprawl back in a hammock, lawn chair, pile of hay or blanket on the ground. Lie down in comfort, and look upward.
By the way, you don’t need to find a meteor shower’s radiant point to see the shower. The meteors will appear in all parts of the sky. It’s even possible to have your back to the constellation Gemini and see a Geminid meteor fly by. However, if you trace the path of a Geminid meteor backwards, it appears to originate from within the constellation Gemini.
When you’re meteor-watching, it’s fun to bring along a buddy. Then two of you can watch in different directions. When someone sees one, they can call out “meteor!” This technique will let you see more meteors than one person watching alone will see.
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.
Be aware that meteors often come in spurts, interspersed with lulls.
Every year, in December, our planet Earth crosses the orbital path of an object called 3200 Phaethon, a mysterious body that is sometimes referred to as a rock comet and parent to the Geminid meteors we see on Earth.
The debris shed by 3200 Phaethon crashes into Earth’s upper atmosphere at some 80,000 miles (130,000 km) per hour, to vaporize as colorful Geminid meteors.
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 it to shed yet more rubble into its orbital stream.
In 2017, 3200 Phaethon will be exceedingly nearby around nights of the Geminid meteor shower’s peak. This object will sweep close to Earth – just 0.069 astronomical units (6.4 million miles, 10.3 million km, 26 lunar-distances) on December 16, 2017 at 23 UTC; translate to your time zone.
The proximity of this object might mean a fantastic year for the Geminids in 2017!
One of the best things about this year’s Geminid shower is that the moon is out of the way. It’s a waning crescent in the east before sunup and so shouldn’t interfere much, if at all, with your meteor-watching. Plus, the waning crescent moon will slide past the morning planets, on the peak mornings on the 2017 Geminid shower.
Look at the chart above. See how the moon gets closer to the sunrise point each day? That motion of the moon across our sky is a translation of its motion in orbit around Earth.
Bring along your binoculars when watching for the moon and planets, on the nights of the Geminids’ peak. They won’t help you watch meteors, but you’ll be able to see Jupiter in the same binocular field of view with the star Zubenelgenubi in the constellation Libra the Scales. Look closely, and you’ll see that Zubenelgenubi is a double star – two stars in one!
You won’t see as many Geminid meteors when the constellation Gemini sits close to the eastern horizon during the evening hours. But the evening hours are the best time to try to catch an earthgrazer meteor.
An earthgrazer is a slow-moving, long-lasting meteor that travels horizontally across the sky.
Earthgrazers are rarely seen but prove to be especially memorable, if you should be lucky enough to catch one.