by Erich Karkoschka

RARE CONJUNCTION ALERT!!

Jupiter and Saturn will get as close as .1 (1/10 of a degree) from each other on December 21st (Winter Solstice) — they are actually separated by distance as Jupiter is 551 million miles from Earth and Saturn is abut twice as far at just over 1 Billion miles from Earth . That will be close enough to challenge being able to separate both with just your eyes. If you get a chance, observe them with your eyes, a pair of binoculars, or a telescope (great opportunity to compare both planets at high power in the same field of view). For comparison, the width of your clenched fist held at arms length is about 10 degrees. On the 21st, they set pretty shortly after sunset, so go out about 1/2 hour after sunset to view them (they will set around 7 pm). The last time they got this close together and were both observable was 1226 (794 years ago). The next conjunction that will be this close will be in 2080. The pair starts December about 2 degrees apart. The distance decreases by about .1 degree every day, so observe them every evening and watch them get closer to each other. Look for a small crescent Moon near the pair on the 16th (5 degrees below) & the 17th (10 degrees to the left).

Venus rises after 5 am and is still conspicuous during dawn. Venus will be only be 1/6 of a degree from a second magnitude star (Acrab) on the morning of the 18th. This is too close to see next to bright Venus with the naked eyes, but a splendid view in binoculars.

Mars fades quickly this month, but is still the brightest object aside from Jupiter and Sirius after it rises late evening. Its diameter of 14 arc-seconds is still larger than its opposition diameter during less favorable oppositions, such as in 2027.

Uranus is 20 degrees to the upper left of Mars at the beginning of December. It can be easily seen in binoculars but requires some practice to find it. By the end of the year, the separation to Mars is only 10 degrees.

Neptune is well to the lower right of Mars, best observable right after dusk.

On the morning of December 12th, the thin lunar crescent will be only 3 degrees from Venus, most spectacular between 5:30 and 6 am. Very experienced observers may try to find them in the afternoon when the moon will occult Venus at around 2:20 pm. They will be only about 15 degrees high. The moon will definitely not be visible naked eye because it is too slim, but the view in a telescope would be good with the disappearance of Venus taking half a minute.

On the 14th, part of Chile and Argentina will experience a total solar eclipse. Some of us had plans to observe it, but had to cancel because of travel restrictions. Instead, we can watch the Geminid meteor show the evening before without moonlight and a peak predicted to occur during that evening, the 13th. Best viewing though is the early morning hours of December 14th.