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A celestial tango and a long-awaited comet

Starwatch

Stargazing is always a great adventure any night of the year, but there are special shows I like to call “celestial happenings.” We have two of them this week in our Butler night skies.

The first one is happening this very weekend, courtesy of the planets Venus and Saturn.

They're in a tight celestial tango in the low southwest during evening twilight. Formally this is called a conjunction. No matter what you call it, you'll love what you see.

All this month, Saturn and Venus have been approaching each other, and this weekend Venus and Saturn are separated by less than a degree, the width of your forefinger held at arm's length. On Sunday evening, they will be only a half degree apart, their tightest celestial hug.

During the coming week, the two planets will gradually part company.

Of course, Venus and Saturn are nowhere near each other physically, but they are certainly in the same line of sight.

You can't miss Venus. It's by far the brightest starlike object in the very early evening, beaming away like crazy in the low southwest.

Saturn is nowhere near as brilliant, even though the ringed planet is much larger than Venus. That's because Venus is less than 95 million miles from Earth, but Saturn is nearly a billion miles away.

Neither planet will be an excellent telescope target individually. Still, the cool thing is that with binoculars or a telescope with a low-power eyepiece, you'll easily see them together in the same field of view.

Venus is permanently cloud-covered, and since Saturn is so far away and close to the horizon, it will also appear super fuzzy, although you may be able to make out its ring system.

If you look early enough in evening twilight on Sunday night and have a clear view of the southwest horizon, you may see an extremely thin crescent moon hanging below Venus and Saturn, but in all likelihood, you probably won't be able to spot it.

On Monday evening, the slightly fatter crescent moon will be just to the upper left of the planetary pair, making for a lovely sight!

No matter which evening early this week you catch the celestial tango between Venus and Saturn, do it as early as you can in the evening twilight. They both slip below the southwestern horizon around 6:30 p.m.

The other celestial happening this week will continue into early February. It's Comet ZTF, named after the Zwicky Transit Facility, based in California.

For nearly 50,000 years, Comet ZTF has been traveling in its marathon orbit from an area in the very outer regions of our solar system called the Oort cloud. It's now in our inner solar system, passing closest to the sun on Jan. 12 and then heading toward Earth.

Certainly, put your mind at ease about Comet ZTF hitting Earth. It will miss us by more than 26 million miles when it passes Earth on Feb. 2, between the orbits of Earth and Mars around the sun. That's when the comet will be at its brightest.

From now until about mid-February, ZTF may be visible with a small telescope or a good pair of binoculars and maybe with the naked eye, especially in the dark skies of the countryside. It will track from night to night between the Big Dipper and Little Dipper near Polaris, the North Star. See the star map.

This will be a good week to try and spot Comet ZTF with at least a telescope or binoculars because there will be very little moonlight in the way. Unfortunately, when ZTF is at its very closest to Earth around Groundhog Day, a full or nearly full moon will make spotting the comet more difficult. It will appear as a "fuzzy star" with at least a short tail, although no one really knows for sure.

Honestly, it will probably jump up and down if you spot it but just knowing how long it’s been traveling our way makes it exciting.

Comets are a mixture of ice, rock, dust, and other frozen gases with diameters anywhere from about a hundred feet to a couple of miles. They spend most of their time in the extra frigid far reaches of the solar system, but when they pass close enough to the sun, they partially melt.

That produces the fuzzy coma cloud surrounding the comet's nucleus and bright tails of vapor and dust. How much of a tail and how bright the tail will be can be very tricky to predict. Sometimes comets can totally break apart. Let's hope that doesn't happen to ZTF.

Good luck with Comet ZTF hunting this week!

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. Contact him at mikewlynch@comcast.net.

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