The winter solstice will arrive at exactly 12:30 a.m. Dec. 22. This marks the longest night of the year for us in the Northern Hemisphere as the sun reaches its lowest point in our sky. There are several interesting highlights in December if you can brave the cold weather.
All five of the brightest planets will be well placed in the morning or evening sky, the Geminid meteor shower will peak the morning of Dec. 14, and there will even be a penumbral lunar eclipse.
Brilliant Venus will double its height in our evening sky, beginning the month at just 9 degrees above the western horizon 45 minutes after sunset and ending up at 18 degrees high at the same time by the end of the year.
It will be getting slightly less full even as it is getting closer and larger, so its actual brightness will remain at minus 3.9 magnitude all month. Look for our sister planet near the slender crescent moon in Capricornus the evening after Christmas, Dec. 26.
Jupiter will already be high in our southeastern sky as it gets dark enough to become visible. It will end its retrograde or westward motion Dec. 26. The King of the Planets was at its best at the end of October, but it is only slowly getting smaller and dimmer over the course of December. Watch as it passes close to the nearly full moon Dec. 6 and then watch the moon continue as it gets closer to full and passes just under the Pleiades on Dec. 8.
There was a very similar conjunction with the moon and Jupiter last month on Nov. 8. I was fortunate enough to watch and photograph that potentially dangerous asteroid, 2005 YU55, for nearly five hours that night.
Because it was moving so fast, about 30,000 mph, which translated to a full degree of the sky in under 10 minutes at that distance of 200,000 miles, less than the distance to our moon, it took us three hours of detailed and persistent work to even find it in the 16-inch Meade telescope at our Starfield Observatory in Kennebunk.
We finally found it right around midnight just as it entered the Great Square in Pegasus. It was quite faint at 11.2 magnitude, 100 times fainter than what the naked eye can see. It was only a quarter of a mile across, or about the size of an aircraft carrier, but that still qualified it as the largest asteroid that ever came that close to us.
It has been calculated that it will be no danger to Earth for at least the next 100 years, but since it does cross over our orbit, it could hit us at some time in the more distant future. Hopefully, we will have developed a way to safely deflect any such asteroid by then.
As this large chunk of rock tumbled through space, I tried to imagine what it would be like to walk on its dark and ominous carbonaceous surface, rich in metals and other valuable elements. This asteroid was knocked out of its safe orbit in the asteroid belt several thousand years ago, where it shared space with millions of similar rocks.
Looking down at our spaceship Earth from that height would give you a real sense of our home as perhaps the only living planet in the known universe. Although it is unlikely that we are the only planet with intelligent life, since we have already found more than 700 planets in other solar systems, if it did turn out that way in the future, it would make life on Earth even more precious.
Only about 20 astronauts have seen Earth from that height, but about 500 astronauts have already been in space, orbiting the Earth, and thereby gaining that valuable perspective.
Mars is already rising before midnight in Leo on the eastern horizon. The red planet will rise an hour earlier by the end of the month. It will get considerably brighter and closer over the course of December and January, approaching its opposition on March 3.
Saturn rises a few hours after midnight in the constellation of Virgo. Look for the ringed planet within just 5 degrees of Spica for most of December. Watch a waning crescent moon pass near Saturn one hour before sunrise on the mornings of the 19th and 20th.
Our first planet, Mercury, can be seen low in the southeastern sky 45 minutes before sunrise during the last two weeks of the month. Look for it close to the waning crescent moon on the mornings of Dec. 22 and 23.
The Geminid meteor shower will peak on the morning of Dec. 14. Since that will be just four days past full moon, most of those meteors will be washed out this year.
Try to catch some of the brighter meteors before the moon rises at 7:19 p.m. Dec. 13 and before 8:27 p.m. Dec. 14. This is the only meteor shower caused by an asteroid instead of a comet.
There will even be a penumbral lunar eclipse at dawn Dec. 10. However, for us on the East Coast, the moon will set before it gets into the darker umbral shadow of the Earth, so you will probably not be able to notice it unless you use binoculars or a telescope or you are photographing the moon carefully.
• Dec. 2. First quarter moon is at 4:52 a.m. EST.
• Dec. 7. Gerard Kuiper was born this day in 1905. The Kuiper Belt of about 70,000 objects larger than 60 miles in diameter, discovered in 1992, was named for him. Pluto is now considered one of those objects. These are fragments of the original protoplanetary disk that failed to form full planets.
• Dec. 10. Full moon is at 9:36 a.m. This is also called the “Long Night Moon” or “Moon before Yule.”
• Dec. 14. The Geminid meteor shower peaks this morning. Tycho Brahe was born on this day in 1546. He was the greatest observer of his time, before the telescope was invented in 1609. He worked with Johannes Kepler to discover that all planets and moons orbit in ellipses and not circles.
• Dec. 17. Last quarter moon is at 7:48 p.m. On this day in 1903, the Wright Brothers made the first powered flight. It took us only about 66 more years to fly all the way to the moon.
• Dec. 22. The winter solstice is at 12:30 a.m.
• Dec. 24. New moon is at 1:06 p.m.
• Dec. 25. Isaac Newton was born on this day in 1642.
• Dec. 26. Venus shines to the left of the waxing crescent moon one hour after sunset tonight and the next evening.
• Dec. 27. Johannes Kepler was born on this day in 1571.
• Dec. 28. Arthur Eddington, a Scottish physicist, was born on this day in 1882. He led a total solar eclipse expedition to Africa in 1919 that proved Einstein’s theory of relativity correct.
Bernie Reim of Wells is co-director of the Astronomical Society of Northern New England.