Bakersfield Night Sky — February 21, 2026
Tickets for the ever-popular “Black Holes” at the William M Thomas Planetarium on March 5 and the March 19 showing of “Destination Mars” are available through the Vallitix site. The Mesmerica shows are sold through the Mesmerica site.
Tonight the waxing crescent moon will be on the west side of Aries and set at about 10:30 p.m. A couple of nights later the moon will be at First Quarter right next to the Pleiades in Taurus and a week after that will be a very special full moon. At 1:50 a.m. on March 3, the full moon will begin to enter the umbra of Earth’s shadow to start a lunar eclipse. The moon will be completely in the umbra, getting an orange or red color, between 3:04 and 4:03 a.m.—59 minutes of totality. The moon exits the umbra at 5:18 a.m. All this happens while the full moon is in Leo, which will be high in the southwest at the start, midway up in the sky further southwest during totality and low in the west at the end of the show.
The attached star chart above shows tonight’s sky at 8 p.m.. The brilliant constellations of Orion and Canis Major lie on either side of the due-South meridian line. The star chart also shows the two brightest stars of the sky: Sirius at the nose or neck of Canis Major (depending on how you connect the dots) and just above the south horizon, Canopus in Carina. Since Canopus gets up to just two degrees altitude, the mountains south of us will block the view from Bakersfield. Sirius is brighter than Canopus in our sky only because Sirius is much closer to us at just 8.6 light years away while Canopus is 309 light years away.
To the left of Orion is the little dog or puppy, Canis Minor with Procyon at the back end. Taurus is to the right of Orion with yellow-orange Aldebaran at its eye. Nearly at the zenith above Taurus and Orion is the pentagon-shaped Auriga with bright Capella at one point of the pentagon, diagonally opposite Taurus’ horn tip.
Also nearly at the zenith is Gemini. Jupiter’s retrograde motion has taken it well to the right side of the string of stars that make up the Pollux side of Gemini. Above super-bright Jupiter is the string of stars for the Castor side of Gemini. Castor and Pollux are the two brightest stars of Gemini and form the heads of the twins. While Castor is definitely the fainter of the twins (so a fraternal twin), it is the more complex of the two.
To the unaided eye Castor appears as one star but in a telescope three stars are revealed. Analyzing each of the stars with a spectrometer to display the barcode of dark lines in their absorption line spectra, further reveals that each of the three stars are in fact a spectroscopic binary—a sextuplet system, so one of the twins is actually three sets of twins! In a spectroscopic binary, the barcode of dark lines shifts back and forth in a periodic fashion as the two very-close stars orbit each other.
While interstellar distances are measured in light years, we measure the separation of binary stars in terms of planetary distances of Astronomical Units (AU), where one AU is equal to the distance between Earth and the sun. There are 63,240 AU in one light year. Mercury is 0.39 AU from the sun, Jupiter is 5.2 AU from the sun, and Pluto is on average 39.5 AU from the sun.
The two brighter binary systems of Castor orbit each other every 445 years at a distance of on average 104 AU in a very elliptical orbit that draws them as close as 71 AU apart and as far as 138 AU apart from each other. The brighter members of the binary systems are “A-type” stars about twice the mass of the sun and with temperatures of 8300 and 9500 Kelvin, they are several thousand degrees hotter than the sun. Their companion stars are cool “K-type” and warm “M-type” stars with just half the mass of the sun and temperatures a couple thousand degrees cooler than the sun. The cool stars are separated from their hotter companions by just 0.03 AU and 0.12 AU.
The third much fainter binary system consists of two warm M-type stars separated by just 0.04 AU. This pair of stars orbits the brighter binaries at a distance of at least 1000 AU and therefore, would take at least 14,000 years to do one orbit. Any exoplanets existing in the Castor sextuplet would orbit around both stars of each binary pair since the stars of each binary system are so close to each other.
Although exoplanets have been found in binary/multiple star systems, it is much harder to detect them than exoplanets orbiting single stars like the sun. Because of the observational bias against exoplanet detection in binary/multiple star systems, we haven’t known for sure how the occurrence rate of exoplanets in those systems compares with the rate in single star systems. Since most stars occur in binary systems, it would be nice to know!
A deep dive into the Kepler mission’s database of exoplanets by a team led by Kendall Sullivan, while they were at UC Santa Cruz, has firmed up the occurrence rate and found that for the case of exoplanets orbiting both stars in a close binary system, the binary systems will host 50% fewer planets than single-star systems. Furthermore, while there is a sharp drop-off in numbers of large gas giant exoplanets found in single-star systems (i.e., nature really prefers making smaller Earth-size planets in those systems), there is a smooth decline in gas giant planet occurrence—nature is not as picky in the type of planets formed in binary star systems. Sullivan, et al’s study seems to show that there are significantly different planet formation processes in single star systems vs. binary star systems. Ah, the plot thickens!
I hope to see you at one of the Planetarium shows. Always clear skies there!
—
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com
