The month of December always marks the beginning of winter for us in the northern hemisphere. This year, that will happen at exactly 4:48 p.m. on the 21st. There are many great and fairly rare highlights this month that will be well worth making the effort and braving some colder weather to see and experience for yourselves.
Mighty Mars reaches its highest and best opposition in nearly two decades on Dec. 8, and it will even be occulted by the moon a few hours earlier on the night of the 7th. All seven members of our family of planets will be visible in the evening sky, which is also fairly rare. Back in June, all of these planets were visible at the same time in our morning sky, so they have migrated 180 degrees since then as all of the planets keep orbiting at their own paces.
Venus has reappeared in our evening skies, and it will form a nice pairing with Mercury low in the southwestern evening sky half an hour after sunset. This will be your last chance to see Saturn in the evening sky for this year, since it will set by 8 p.m. by the end of this month. Then Uranus and Neptune are also visible in the evening sky, but you would need a telescope to see them.
Then we will have not one, but two good meteor showers – the Geminids and the Ursids – the asteroid 4 Vesta is at its brightest, and Comet C/2022 E3 (ZTF) continuing to brighten close to Polaris, but you would still need a telescope to see it.
Mars reaches opposition every 26 months as we catch up with it in our faster orbit around the sun. This time, it will only get within 50.6 million miles of us, compared to its closest approach to us in nearly 60,000 years of only 35 million miles back on Aug. 27, 2003. However, it will reach over 70 degrees high in the sky in Taurus, which is much higher than Mars reached in 2003. Mars was two and half times brighter in 2003 than it will get this time, and it was also nearly twice as large then, but not as high, which means its light had to pass through more of our atmosphere. Look for many nice features on Mars through a telescope, like some of its dark markings, its polar icecaps, and even some of its thin atmosphere, which should all be visible until the end of January.
An unusual bonus for this opposition will be the full moon occulting, or covering up, Mars exactly at opposition of the moon and Mars. We are right on the southern line of this occultation, which most of this country will be able to see – except for most of the East Coast. The full moon will cover Mars at 10:57 p.m. and it will reappear about half an hour later at 11:24 p.m. I have watched daytime occultations of Venus by the moon and even graze occultations of some of the stars in the Pleiades as they blinked on and off as their light glanced through the valleys between the mountains on the moon, the same effect that produces the colorful and dramatic Bailey’s beads and the diamond ring effect during a total solar eclipse.
Venus and Mercury form a nice pair low in the southwestern evening sky half an hour after sunset in Sagittarius. Mercury reaches greatest elongation from the sun on the winter solstice, Dec. 21. They will be at their closest, just 1.5 degrees apart, on the 28th. Look for a beautiful conjunction with a slender waxing crescent moon on Christmas Eve. They will be about 20 degrees to the west of Saturn in Capricorn along the ecliptic. We will lose Saturn by the end of this month.
Jupiter is still quite brilliant at minus-2.5 magnitude, or about 20 times brighter than Saturn. It just ended its retrograde, or westward motion, against the fixed background of stars on Nov. 24. Now it is back to its normal eastward motion in Pisces and getting a little fainter each night as we pull farther ahead of it in our orbit around the sun.
The Geminids, usually the best meteor shower each year, will peak on Dec. 14, but it will be active from the 4th to the 17th. Unfortunately, the full moon happens one week earlier, so it will rise around midnight as a last quarter moon to spoil the best part of this shower, since they are usually much better after midnight, because we are then turning into the source of the meteors. You can usually expect up to 100 Geminids per hour, but that rate will be cut way down this year. Then you have another shower, the Ursids, active from the 17th to the 26th and peaking on the 23rd right at the new moon, which is ideal. Caused by Comet 8P/Tuttle, they usually only produce 10 meteors per hour. They will still both be worth watching if it is clear on those nights.
On top of all that, we had a historic event last month, the launch of Artemis 1, marking the beginning of our return to the moon after a 50-year absence. NASA was trying to do this since the end of August and they finally got it into space after enduring two hurricanes and many other setbacks, which is a testament to our perseverance and engineering skills. This is a 25-day unmanned mission with many goals in mind to prepare for humans to be launched on Artemis 2 by 2025.
DECEMBER HIGHLIGHTS
Dec. 1: The moon passes 3 degrees south of Jupiter this evening.
Dec. 7: Full moon is at 11:08 p.m. This is also known as the Cold, Long Night, or Moon-before-Yule. Mars will be occulted by this moon starting at 11 p.m. Gerard Kuiper was born in 1905. The Kuiper Belt of Pluto-like objects was named after him.
Dec. 8: Mars is at opposition, rising at sunset and setting at sunrise. Margaret Geller was born in 1947. She is an astrophysicist who teaches at Harvard and discovered the “Great Wall” of galaxies in 1989, the largest structure in the universe at the time 760 million light years long.
Dec. 11: Annie Jump Canon was born in 1863. She was a famous member of the all-women “Harvard Computers” who developed the classification system of stars on the HR diagram along with discovering helium in the sun. The moon is at apogee, or farthest from the earth today at 252,195 miles.
Dec. 14: The Geminid meteor shower peaks. Tycho Brahe was born in 1546. He was the greatest observer on Earth before the telescope was invented. Along with Kepler, his observations proved that all of the planets actually orbit in ellipses and not perfect circles.
Dec. 16: Last quarter moon is at 3:56 a.m.
Dec. 23: New moon occurs at 5:17 a.m. The Ursid meteor shower peaks this morning.
Dec. 24: The moon is at perigee, or closest to Earth at 222,619 miles this morning. The moon is very close to Mercury and Venus this evening.
Dec. 25: Isaac Newton was born in 1642.
Dec. 26: The moon passes 4 degrees south of Saturn this morning.
Dec. 27: Johannes Kepler was born in 1571.
Dec. 28: Sir Arthur Eddington, a famous British astronomer, was born in 1882. He took some photographs of a star behind the sun during a total solar eclipse in May of 1919 that proved Einstein’s new General Theory of Relativity correct.
Dec. 29: Mercury passes 1.4 degrees north of Venus this evening. The moon passes 2 degrees south of Jupiter this morning. First quarter moon is at 8:21 p.m.
Bernie Reim of Wells is co-director of the Astronomical Society of Northern New England.
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