Skywatch Line for Wednesday and Thursday, March 11 and 12, 2026, written by Alan French
This is Dudley Observatory’s Skywatch Line for Wednesday and Thursday, March 11 and 12, 2026, written by Alan French.
The Sun rose at 7:14 A.M. on Wednesday and sets at 6:57 P.M. On Thursday it rises at 7:12 A.M. and sets at 6:58 P.M. This Thursday has 10 minutes, 22 seconds more daylight than last Thursday.
The Moon was at last quarter Wednesday morning. The Moon rises at 3:44 A.M. Thursday morning. At 6 A.M. a 40% sunlit, waning crescent Moon will be 14 degrees above the south southeastern horizon. Although Mars and Mercury are in the morning sky, the are too low in morning twilight to be visible before the Sun rises. The Moon will not set until just after noon.
Although changing to Daylight Saving Time moved sunrises and sunsets an hour later by adding an hour to our clocks, the skies are still completely free of evening twilight and fully dark by 8:30 P.M. With no Moon in the sky these would be good nights to revisit the beauty of the Winter Circle, still high in the south under dark skies.
The brightest star in the Winter Circle and the brightest star in the night sky is Sirius, just 2 degrees past due south and 30 degrees above the horizon at 8:30 P.M. It lies in Canis Major, the Big Dog. Going clockwise around the Circle we next come to Procyon, to the upper left of Sirius, the brightest star in Canis Minor, the Little Dog. Above Procyon, you will find Pollux and Castor, close together, with an interloper, brilliant Jupiter, outshining even Sirius, to their lower right and inside the Circle. Castor and Pollux are the brightest stars in Gemini, The Twins.
Continuing clockwise we next come to Capella, the brightest star in Auriga, The Charioteer. Well to the lower right of Capella is reddish Aldebaran, the brightest star, Alpha Tauri, in Taurus, the Bull. In his 1603 star atlas, Uranometria, German astronomer Johann Bayer gave each star a unique designation, a Greek letter plus the Latin genitive of the constellation’s name. The Greek letters were intended to run in order of brightness, with Alpha assigned to the brightest star in each constellation. When Bayer lacked accurate brightness measurements, similar stars were designated by position, west to east. When Bayer ran out of Greek letters he used Latin letters. Multiple stars got the same letter and individual numbering with a superscript.
The final star in the Winter Circle is Rigel, below and a bit east or left of Aldebaran. Rigel’s Bayer designation is Beta Orionis, yet it is the brightest star in Orion. The Alpha designation went to Betelgeuse, marking Orion’s right shoulder to the upper left. It is Alpha Orionis yet is the second brightest star in Orion. This fits with Bayer designated stars he lacked accurate measurements for assigning letters west to east, but the consensus is that Betelgeuse was brighter in Bayer’s time. Both stars are variable double stars.
You may recall that Betelgeuse was in the news in late 2019 and early 2020. Betelgeuse normally varies between around magnitude 0 and 1.3, but it faded to roughly magnitude 1.6–1.7. That was the faintest ever recorded and there was speculation that it might go supernova. Observations showed a huge convective plume had been expelled from the star, condensed into dust, and obscured its light. Once the dust dissipated, it returned to its normal brightness. The event has become known as The Great Dimming.