The Backyard Astronomer: Geminids meteor shower brings "slow" shooting stars and a few fireballs
One of the most captivating celestial events is a meteor shower.
Everyone, from time to time, has seen meteors—a.k.a. “shooting stars”—while taking a stroll or walking the dog at night. These swift, bright trails of light in the night sky are caused by bits of debris from the creation of the solar system or even space junk such as nuts and bolts from old rockets and deployed satellites.
Although these are unpredictable sightings that can sometimes startle the observer, there are many known and very predictable meteor showers throughout the year. All that is required to view them are clear, dark skies.
On the night of December 13 (and the early morning of December 14), one of the best displays will play out in the skies above. This is the annual Geminids meteor shower, so named because its radiant, or origin, appears to be a specific point in the constellation Gemini.
This point is located just above the star Castor, which is located 51 light-years away and is the mythological mortal twin warrior of Pollux.
The shower is known to produce a consistent 120 graceful meteors per hour. That's two per minute, and there will even be a few bright fireballs (exceptionally bright meteors that last longer than normal and seem to even leave a trail in the sky).
The meteors' "slow" speed of 36 kilometres per second will add to the beauty of the sky show. By contrast, the Perseid meteors in August streak through the atmosphere at twice that speed.
And even though the moon will be about 77 percent lit, we should still see a high number of meteors vaporize in the atmosphere.
The Geminids are not produced by a comet, as in other showers, but by the five-kilometre wide asteroid 3200 Phaethon. This object could be a dead comet that, over time, has lost its chemical and water ices.
A comet loses one to two percent of its volatile surface every time it rounds the sun. Solar radiation causes the comet's gases to glow and its surface to release sand and grit, which can form an iconic dust "tail".
One of the best times to view the Geminids will be after midnight (PST), when the moon has set and the shower is at its peak. But if that is too late for you, anytime earlier—with a little darkness, luck, and patience—would be good to witness a few unforgettable bright meteors.
Clear skies.
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