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Driftless Dark Skies: Solstice Sunrise & Sunset

December 3, 2018 by John Heasley

Dawn and dusk on December 21st are excellent times to mark our passage from autumn to winter. Winter solstice is the moment when Earth’s axis is pointed directly away from the sun.  Here in the Driftless Area of the northern hemisphere, the sun rises and sets at its most southerly points for the year. It casts long shadows as it arcs low across the sky. The days have shortened to less than nine hours of daylight and night has lengthened to more than fifteen hours of darkness.

From Frank’s Hill looking west to Crawford County

Look to the southeast on solstice morning, and you will see Venus bright and brilliant. Closer to the horizon and a little to the left of Venus, the largest and smallest planets of our solar system are close together. Jupiter is brighter and to the right, and Mercury is dimmer and higher. Your best view is between 6 and 7am before the solstice sun rises around 7:29. The sun sets that evening around 4:28pm coinciding closely with the moment of solstice at 4:23pm and the almost full moon rising in the northeast around 3:54pm. Your shadow from the setting sun points the way to the rising moon as Sun, Earth, you, and Moon all align for a solstice syzygy!  The moon

is 99% full as it rises and will continue to wax all though the longest night becoming 100% full as it sets around 7:11am on Saturday morning. It rises again Saturday evening around 4:47 just after sunset. Appropriately, December’s full moon is called the “Cold Moon”, “Long Night Moon”, and “Yule Moon”.  In contrast to the solstice sun, the solstice full moon rises and sets at its northernmost points for the year as it arcs at its highest across the wintery sky giving us over fifteen hours of moonlight to illuminate the night.

There are other wonders in the sky to savor around the time of solstice. You can be wowed by the Waning Crescent Moon and Venus together in the eastern sky before sunrise on December 3 and January 1. The Geminid meteors will be at their best the night of December 13/14. Bundle up to see pieces of “rock comet” Phaeton lighting up the sky as Earth passes through the debris stream it left behind.  Best views will be after moonset around 10:27pm. If you can get to a site away from light pollution, you might see a meteor every minute. That same week, we may even catch sight of Comet Wirtanen between the Hyades and Pleiades on December 16 as it passes just seven million miles from our planet.  Binoculars and dark skies will make it easier. As astronomer David Levy observed, “Comets are like cats: they have tails, and they do precisely what they want”. Here’s hoping that Comet Wirtanen brightens enough to awe us as we await the solstice.

John Heasley is an astronomy educator and stargazer who enjoys connecting people with the cosmos. He volunteers with NASA/JPL as a Solar System Ambassador. For more information about stargazing in southwest WI, like Driftless Stargazing LLC on Facebook and find out whenever there’s something awesome happening in the skies. Driftless Dark Skies appears monthly in the Voice of the River Valley.

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