THE USM SOUTHWORTH PLANETARIUM
207-780-4249 www.usm.maine.edu/planet
43.6667° N 70.2667° W
Altitude: 10 feet below sea level
Altitude: 10 feet below sea level
Founded January 1970
Julian date: 2458689.5
"Heavens below!"
THE DAILY ASTRONOMER
Wednesday, July 24 2019
When Betelgeuse Returned
a few mornings ago (21 July) it didn't linger long in the pre-dawn sky. On that date, it was more flickering flame than rising star. Yet, after a two month absence its return to our sky will delight those myriad sky watchers who've yearned for its return. Although Betelgeuse's arrival ominously portends winter's eventual return, we are gladdened by the latest renewal of the next 10 month Betelgeuse cycle.
a few mornings ago (21 July) it didn't linger long in the pre-dawn sky. On that date, it was more flickering flame than rising star. Yet, after a two month absence its return to our sky will delight those myriad sky watchers who've yearned for its return. Although Betelgeuse's arrival ominously portends winter's eventual return, we are gladdened by the latest renewal of the next 10 month Betelgeuse cycle.
Betelgeuse represents Orion's eastern shoulder. Betelgeuse is a red super giant large enough to accommodate more than 160 million Sun-sized spheres. (Image: Wikipedia)
Betelgeuse's "heliacal rising" date for this latitude was July 21st. This means that an observer watching the eastern pre-dawn sky on this date would have been able to observe Betelgeuse rise above the horizon just before the intensifying morning twilight absorbed it. The star's "heliacal setting" date was (or will be) May 21st. On that evening, an observer looking toward the western evening sky can see Betelgeuse in the evening twilight for a moment before it sets. On the following evening, Betelgeuse will not be visible. By the time the sky darkens enough to render Betelgeuse visible, it will have already set.
As is true with all non-circumpolar stars (those stars that actually rise and set), Betelgeuse rises four minutes earlier each day as a consequence of Earth's revolutionary motion. Though Betelgeuse doesn't remain in sight long before the pre-dawn light obscures it, the mammoth red star will be visible for about four minutes more each successive morning. Betelgeuse is rising earlier and, as its summer, the Sun is rising slightly later each morning. By early August, Betelgeuse will be up for viewing for about half an hour.
Betelgeuse, like its host constellation Orion, is most prominent in the winter, when it remains visible most of the night. It is the "Winter Red Supergiant," the counterpart to Antares, the bright star in Scorpius that serves as our "Summer Red Supergiant." Although Antares is front and center and the summer is now roaring on all six cylinders, Betelgeuse has emerged into the morning sky and, if the last few thousand of years are any guidance, will take it place into evening sky prominence.