Stellar Vista Observatory Sky Report: Dec. 28 – Jan. 3

Stock image, St. George News

SOUTHERN UTAH — The Sky Report is presented as a public service by the Stellar Vista Observatory, a nonprofit organization based in Kanab, Utah, which provides opportunities for people to observe, appreciate and comprehend our starry night sky. Additional information is available online. Send questions and comments to [email protected].

All the astronomy news a week ago was about the extremely close conjunction of Jupiter and Saturn, when they were separated by a scant 0.1 degrees. Jupiter orbits the sun faster than Saturn and is leaving Saturn behind as it moves eastward and away from it, but they remain close and are well worth watching. They’re separated by a scant 0.8 degrees on Monday.

Unfortunately, both set four minutes earlier each night and they now appear very low in the west-southwest in evening twilight. They set before the sky is fully dark, and we’ll lose them soon as they slip behind the sun. When they reappear in the morning sky in late February, they’ll be 8 degrees apart and no longer a “double planet.” So enjoy them while they’re still around.

Mars remains conspicuous as the orange “star” high in the south as night begins. It’s in Pisces, where there are no even moderately bright stars to compete. Mars is the sole planet visible from full darkness until it sets at around 2 a.m. It’s now too distant, at 80 million miles away, for all but the best telescopes to show any surface features on it.

Venus dominated the morning sky all fall, but like Jupiter and Saturn, it too is leaving us. Venus orbits the sun faster than the Earth, and it’s very slowly moving behind the sun. We’ll last see it about this week, low in the southeast just before the sun rises.

The Earth is closest to the sun on Saturday. So why is it cold now? It’s because the Earth’s Northern Hemisphere it tilted away from the sun, causing there to be few hours of warming sunlight and the sun to shine on us from a low angle. At the same time, the Southern Hemisphere experiences long days and the sun’s path is high in their sky. Actually, the Earth’s orbit is out-of-round by only 3%, too little to notice if the Earth’s orbit was drawn on a large sheet of paper, and the changing distance has little effect on temperatures.

This week the days begin to grow longer, very slowly at first and with accelerating change as we approach the spring equinox in March. The minor Quadrantid meteor shower peaks on Saturday night and Sunday morning but few people brave the cold to see it, and this year moonlight interferes.

Written by JOHN MOSLEY. John Mosley was program supervisor of the Griffith Observatory in Los Angeles for 27 years and is the author of “Stargazing for Beginners” and “Stargazing with Binoculars and Telescopes”. He and his wife live in St. George where he continues to stargaze from his retirement home while serving on the advisory committee for Stellar Vista Observatory.

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