Solstice Aurora And A Dawn Double Conjunction

On the winter solstice, the sun reaches its lowest point in the sky. It rises late, spends only a few hours above the horizon and sets early. Short days and long-slanted solar rays bring on the cold. At the summer solstice (left), the sun reaches its highest point in its yearly cycle. Direct rays and long days bring on the heat! The diagram shows the sun due south around noon. Illustration: Bob King

Just a few hours ago, the sun reached its lowest point in the sky for the northern hemisphere at exactly 4:44 a.m. Central time (10:44 UT). The moment is known as the winter solstice and the official start of winter. It’s also the shortest day and longest night of the year. If night’s your thing, you’ll have plenty of it — about 15 hours worth. But if the dearth of daylight gets you down, today you can cheer up by celebrating the return of the light.

This map shows a large swath of the sky rolled out like a map. On the winter solstice, the sun (yellow circle) reaches its lowest point in the sky on its yearly path called the ecliptic. Immediately after, it begins to move north again, and the amount of daylight begins to increase. Because of Earth’s tilted axis the sun swings high and low along the ecliptic with the changing seasons. Credit: Durham University Community

Since the first day of summer last June, daylight has been trickling away like sand in an hourglass. That’s changing now as the sun reverses direction; instead of sinking south our stellar star is climbing north again. North means up, up, up in the direction of the summer solstice. Starting tomorrow, daylight slowly starts to gain the upper hand. We won’t notice it right away, but sharp-eyed skywatchers will perceive an extra helping of light by the third week of January when the sun lingers for a good half hour longer in the west before setting.

The cyclical bobbing up and down path of the sun happens because the Earth’s axis is tilted 23.5 degrees. In winter, the northern hemisphere leans away from the sun, causing it to appear low in the sky. In the summer, we lean toward the sun and it appears higher in the sky. Credit: NSF/NOAA

For today, go out and celebrate the sun’s new attitude just as humans have done for at least the last 30,000 years. Ring in the light, but don’t forget the night. I like these long nights. There’s so much to see, and you don’t have to stay up late to enjoy the sight of Venus, the “Christmas Star,” in the western sky at dusk or catch the striking trio of stars in Orion’s Belt rising in the east. There’s also a possibility that skywatchers in the northern U.S. and southern Canada will get a visit from the northern lights tonight.

A high-speed wind of solar protons and electrons from a coronal hole in the sun’s atmosphere arrives late this afternoon and will stay the evening. With luck, it will provide the spark needed for a minor G1 geomagnetic storm. Watch for an auroral arc and possibly some occasional short rays and pillars in the lower half of the northern sky this evening through about 10 o’clock Central time.

Not only is today a special day, but tomorrow morning, Dec. 22, watch for a double conjunction of Jupiter and the moon and Jupiter and the star Spica. Stellarium

Then, tomorrow morning, the thick crescent moon will line up atop Jupiter, which lines up above Virgo’s brightest star in a double conjunction! Nice thing is, because the night is so long, the sky will still be dark enough from many locations to see as late as 7 a.m. Winter may be overly generous with darkness, but we remember on this day that it also sows the seeds of summer sunshine. Wishing you a joyous solstice!