Bakersfield Night Sky — November 16, 2024
Tickets are still available for Thursday’s (November 21) showing of “Moon Base: The Next Step” at the William M Thomas Planetarium. “Moon Base” is about the next stage of human exploration and settling of the moon. The moon will become our first “staging post” from which Mars and the rest of the solar system becomes tantalizingly closer. On Friday, tickets will go on sale for “Season of Light” that is a holiday tradition.
Jupiter is now well up in the east in the early evening, so we’re now able to see the two brightest planets (Venus and Jupiter) in our evening sky. In fact, we’re now just about able to see them both up at the same time. Venus will be low in the southwest at 7 p.m. among the stars of Sagittarius as Jupiter is rising low in the east-northeast between the two horns of Taurus. They’ll draw closer together over the next year. Tonight the moon, one day past full moon phase, will be directly above Jupiter as Jupiter rises. The star chart above shows the sky an hour later at 8 p.m. On the night of November 22, the moon will be at third (last quarter) and at the end of the month, it will start the phase cycle over with the new moon. Although the moon will be quite bright tonight at one night into its waning gibbous phase, Jupiter will still be easily visible. A bit further north will be the bright star of Auriga, Capella.
At magnitude zero on the brightness scale used in astronomy, Capella is definitely one of the brightest stars in our sky and I sometimes confuse Capella with Jupiter if I can’t see Jupiter yet above the mountains in the east. But when I can see them both, it’s obvious which one is Jupiter because Jupiter is at magnitude -2.8. The magnitude scale of astronomy has lower magnitudes for brighter objects and the very bright objects have negative magnitudes. Since the magnitude scale is logarithmic, Jupiter is actually 13.4 times brighter than Capella.
The name “Auriga” for the constellation comes from the Latin for “charioteer” and some pictures of Auriga will have a chariot but other sky legends will have Auriga being a goatherd and the picture will be of a shepherd holding a goat (or two) in his arms. The three fainter star above Capella making a skinny triangle are known as “the Kids”. Just below the west (right) end of Auriga is the galactic anticenter—the direction directly opposite the galactic center. That’s why you see the milky band of the Milky Way sort of peter out in that direction.
Above Auriga is Perseus, the famous Greek hero. The pictures of Perseus drawn for the constellation show Perseus holding the head of Medusa, the creature so hideous that to look at it would turn one to stone. The eye of Medusa is the variable star Algol, “the demon star”. Algol is the first eclipsing binary star system discovered, though people knew of its variability long before we figured out what was causing it. In eclipsing binary star systems, two stars orbit each other closely with one appearing to pass in front of the other. With Algol, a dimmer orange giant star covers up the brighter but smaller blue-white star for about two hours every 2.867 days, so Algol dims from an easily visible magnitude 2.1 to just barely visible magnitude 3.4 in the Bakersfield sky, a change of about 3.3 times in brightness. When the brighter blue-white star passes in front of the giant star, the drop in brightness is very small. Eclipsing binary systems are very important in astronomy because we get very accurate masses and diameters of the stars. With thousands of eclipsing binaries known, we’ve been able to measure the properties of all of the different types of stars in the Galaxy. Careful examination of the spectrum of light from the Algol system shows that the two stars orbit so closely that the blue-white star is drawing material from the giant companion, so eventually the giant will be nearly stripped to its core.
North of Perseus is the W-shape of Cassiopeia. The stars of Cassiopeia are bright enough to be seen in most parts of Bakersfield but her husband’s (Cepheus) stars need a dark sky to pick them out. In the early November evening sky, Cepheus is to the left of Cassiopeia, due north. Cepheus’ outline looks like a simple drawing of a house. Below Cepheus is Ursa Minor, the baby bear, though most people know the asterism part as the “Little Dipper”.
The end tip of the baby bear’s tail (the end of the handle of the Little Dipper) is Polaris, the North Star, around which all of the stars and constellations appear to rotate. Today’s north pole points almost directly at Polaris but the wobble of Earth’s rotation axis had the north pole pointing more toward Kochab at the other end of Ursa Major 2000 years ago. Two thousand years from now, the north pole will point toward the top of Cepheus and over the next several thousands of years, where it points will move right through the middle of Cepheus to the “bottom of the house” figure.
I wish you a great Thanksgiving holiday!
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Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com
