Bakersfield Night Sky — December 7, 2024
The holiday favorite “Season of Light” has its last showing this Thursday, December 12 at the William M Thomas Planetarium and then the Planetarium will be closed for the BC winter break. We’re bringing back the “Mesmerica” shows next semester but with a different scheduling: one Friday/Saturday night per month of shows. As before, the Mesmerica tickets will be sold through the Mesmerica website while the regular Planetarium shows will be sold through Vallitix.
Tonight Jupiter is at opposition, so it is directly opposite the sun on our sky—rising at sunset. A view from high above the solar system would show the sun, Earth, and Jupiter in a straight line. This means that we’re at the closest distance to Jupiter (or nearly at the closest distance due to the elliptical orbits axes not being aligned). It also means that Jupiter is very bright in the sky, brighter than its already usual bright appearance: a –2.8 on the magnitude scale that astronomers use to specify brightness where more negative numbers mean brighter objects. The brightest star in the night sky is Sirius with a magnitude of –1.46, so Jupiter is 3.4 times brighter than Sirius. Sirius will become visible in the east at about 9 p.m. for you to do the comparison. If you want to calculate how much brighter one object is than another from the magnitude numbers, subtract one magnitude from the other and then raise 2.512 to the power of the subtraction value. Where did 2.512 come from? It comes from defining the magnitude scale such that a magnitude difference of 5 corresponds to exactly 100 times in brightness, so the fifth root of 100 comes out to be 2.512. Oh yes, I know, very intuitively obvious (said with just a hint of sarcasm).
Jupiter blazes away between the two horns of Taurus this month. Because Earth has been catching up to and passing Jupiter these past couple of months, Jupiter has appeared to move backward (westward) relative to the stars of Taurus and will continue to do so until early February. When Earth has reached sufficiently ahead of Jupiter in its faster, inner orbit, Jupiter will appear to move its usual slow eastward drift among the stars.
Low in the southwest after sunset, Venus will shine even brighter than Jupiter at magnitude -4.2 (or 3.6 times brighter than Jupiter). Venus drops down into the Bakersfield haze layer by about 7:30 p.m. or a little later, so you will have nearly three hours after sunset to compare Venus and Jupiter.
Tonight the moon is almost at first quarter phase (one quarter of the way around in its orbit), so the moon makes approximately a 90-degree angle with respect to the sun and it appears half lit in our sky. The precise time of first quarter phase is about 7:30 a.m. tomorrow morning, so it probably makes more sense to say that first quarter is tonight rather than tomorrow night. In any case, tonight is when the moon will be closest to Saturn on our sky. Saturn will be to the upper left of the moon by just 3 degrees separation, which is close enough for both to comfortably fit within the same field of view of your binoculars.
With a brightness of first magnitude, Saturn is much brighter than the rest of the surrounding stars of Aquarius. The brightest star in Aquarius is Sadalsuud, a yellow giant star 537 light years from us, so it shines at magnitude +2.9, making it just barely visible in the Bakersfield sky. Saturn has been slowly moving through Aquarius since the beginning of 2023. Since it takes Saturn about 29.5 years to move through all of the zodiac constellations in its circuit, Saturn will spend about 2.5 years on average in a given zodiac constellation.
The moon will be full the night of December 14/15. On that night it will be near the tip of the right horn of Taurus, so Jupiter and the moon will be at the same altitude in the early evening as they rise with the stars of Taurus. In fact, the brightest star of Taurus, orange-red Aldebaran (magnitude 0.85), at the eye of Taurus, will also be at the same altitude, so the moon, Jupiter, and Aldebaran will make a nice horizontal line on the sky in the early evening with Jupiter about equidistant from Aldebaran and the full moon. Above and to the left of the moon on that night will be the brightest star of Auriga, Capella (at magnitude 0).
The previous night, December 13/14 is the peak of the Geminid meteor shower but the nearly full moon is going to dampen the show. They are the result of Earth passing through the dust trail of 3200 Phaethon at about 22 miles/second. Usually, the Geminids produce the most numerous meteors of the year (or in the top two) with up to 50 to 70 meteors/hour under a dark sky.
The star chart above shows the eastern sky at about 9 p.m. Below the brilliant stars of Orion will be Sirius and Procyon to the left of Sirius at the same altitude as Sirius. Continue to the left (north) at the same altitude and at the same distance as Procyon is from Sirius, you’ll see bright orange-red Mars (magnitude –0.6)! Mars will be right next to the Beehive Cluster at the center of Cancer—a nice view in binoculars.
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Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com
