What a great weekend for stargazing! The Geminid meteor shower is peaking and a historic celestial hugging is getting tighter and tighter.
The closest conjunction between the bright planets Jupiter and Saturn since Galileo was stargazing will culminate Dec. 21. On that evening. they will be only about a tenth of a degree apart. That’s so close that it will appear as if Jupiter and Saturn have merged into one super planet to the naked eye. That certainly isn’t the case as the two planets are nowhere near each other physically. They just happen to be a hair from being precisely in the same line of sight. This is the closest conjunction of Jupiter and Saturn since 1623!
This weekend the two planets are separated by less than a degree — that’s less than the width of one of your fingers held at arm’s length. You can’t miss them as they pop out in the early evening twilight in the low southwestern sky. Jupiter is by far the brightest with Saturn just to the upper left of Jupiter. Don’t wait too long to check them out because the planetary duo sets a little after 7 p.m.
The new crescent moon will pass by to make the Jupiter-Saturn conjunction even more sweet this week. On Wednesday evening, (Dec. 16), the very thin crescent moon will lie just below the planet pair. Thursday night (Dec. 17), a slightly fatter crescent moon will be perched to the upper left of the great conjunction. Not only will you see the sunlit crescent on both nights, but you’ll probably see the rest of the moon’s disk bathed in softer grey light. This is called Earthshine, because that’s what it is. Actually, it’s sunlight bouncing off the Earth and on to the moon. It’s so wonderful!
Meanwhile, the great Geminid meteor shower is peaking on Sunday night into Monday morning, Dec. 13-14. It’s one of the best annual meteor showers. Viewing the Geminids this year should be fantastic because the moon will be out of the sky and won’t have a chance to visually wash out the meteors or “shooting stars.”
Get out into the dark countryside and you may see 50 to 75 meteors an hour, especially after midnight on Monday morning. Bundle up and bring a reclining lawn chair. Trust me, the Geminids are worth losing sleep over! Even if you’re not able to pull off a late show, you should still be able to see a good number of meteors in the early evening.
This shower is called the Geminids because all of the meteors in the celestial dome will appear to stream from the general direction of the constellation Gemini the Twins, rising in the eastern sky in the early evening and nearly overhead after midnight. By no means should you restrict your viewing to just that part of the sky because the meteors will be all over the heavens, and I don’t want you to miss any! The best thing to do is kick back on a fully reclining lawn chair, roll your eyes all around and keep count of how many meteors you see. No binoculars or telescopes are needed or wanted. You want to have a broad view of the sky. Also, give it some time. You need to let your eyes adapt to the darkness. That can take up to half an hour.
Meteor showers occur when Earth, in its orbit around the sun, runs into a debris trail of dust and small pebbles. For most meteor showers, the debris is left behind by a passing comet. The Geminids are unusual, though, because the debris trail was produced behind a three-mile asteroid. Astronomers discovered it the asteroid in 1983 and dubbed it 3200 Phaethon. It has a highly elliptical orbit that swings it by our part of the solar system every year and a half. When it’s close to the sun, it refreshes the debris trail. It’s a real cosmic litterbug!
The individual debris particles are called meteoroids and are tiny. I would say more than 99% of them are less than the size of your thumbnail. They slam into our atmosphere about 50 to 80 miles high at speeds that can exceed 20 miles per second. They burn up in our atmosphere due to air friction, but no way can we see the actual combustion that high up. The streaks we see are caused by the columns of air becoming temporarily chemically destabilized by the meteors ripping through.
Meteor showers are best seen after midnight when your side of Earth has rotated into the debris trail direction. A good analogy is driving on a warm summer evening (isn’t that a pleasant thought about now?), you get many more bugs smashing on your front windshield than you do on your rear window. After midnight we’re facing through the “front windshield.”
Enjoy the historic close conjunction of Jupiter and Saturn, the Geminid meteor shower, and all of the magic of the night skies this holiday season, especially this year with all we’ve been through. It’s a great escape!
Mike Lynch is an amateur astronomer and retired broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul. He is the author of “Stars: a Month by Month Tour of the Constellations,” published by Adventure Publications and available at bookstores and adventurepublications.net. Mike is available for private star parties. You can contact him at [email protected]
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