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The Sky This Week
U.S. Naval Observatory's Weekly Blog
Tales of the Hunter and the Bear
by Geoff Chester, USNO Public Affairs
15 February 2022
The Big Dipper standing on its "handle", imaged 2019 February 16 from Mollusk, Virginia
with a Canon EOS Rebel SL2 DSLR.
The Moon begins the week beaming down from her perch among the stars of Leo, the Lion. She wanes from her full phase to Last Quarter, which occurs on the 23rd at 5:32 pm Eastern Standard Time. As Luna’s phase wanes she dives southward along the ecliptic, passing through the rising constellations of spring.
The Full Moon washes out all but the brightest stars as the week begins. Fortunately, the early evening hours are dominated by the bright stars and constellations of the Great Winter Circle. Orion and his bright, colorful cohorts cross the meridian at 8:00pm. No matter how bright the sky appears, the stars of this region provide a splendid start to an evening’s stargazing. Orion’s distinctive shape and his placement straddling the celestial equator have made him the most recognized constellation we see in the sky. He is visible from every inhabited part of the Earth, and his outline figures prominently in the sky lore of virtually every culture that has turned its collective gaze skyward. To the ancient Egyptians he represented Sahu, the immortal soul of Osiris, god of the Underworld. A wonderful depiction of Sahu, followed by the star Sothis (which we now call Sirius) may be found in the famous “Zodiac of Denderah” that once graced the walls of the temple of the goddess Hathor at that site. The temple is some 2500 years old, but it is based on sky lore that pre-dates the temple by 2000 years, where we find descriptions of Sahu linked with the souls of deceased pharaohs from Egypt’s earliest dynasties.
Orion’s stars shine with an icy blue tint with the exception of Betelgeuse, which marks Orion’s shoulder. A casual glance will show a distinctive reddish tint to Betelgeuse, which we now know indicates a relatively cool surface temperature compared to its cohorts. Betelgeuse is the brightest of a class of stars known as red supergiant stars, which are highly evolved and nearing the end of their lifetimes. Most of the other stars in Orion are blue supergiants, which are comparatively young in their evolution. These stars are highly luminous, shining with the equivalent energy of many thousands of Suns, and for the most part they are thousands of light-years away. Orion’s stars seem to have originated in the Great Orion Nebula, which is one of the largest star-forming regions in our galaxy.
While Orion dominates the early evening hours, another familiar star pattern begins to become prominent in the northeastern part of the sky. The asterism that we call the “Big Dipper” seems to stand on its “handle” as the night progresses, and when I see it I’m assured that spring is not too far in the future. Although it doesn’t sport the blazing stars of Orion, the seven stars that make up the Dipper asterism still form a shape that is instantly recognized by residents of the Northern Hemisphere. Like Orion, the Dipper is associated with the sky lore of many ancient peoples. It was a central focus of many Native American cultures which used its annual excursions around the north celestial pole as a calendar to time their agricultural activities. In the Greco-Roman skylore that forms the basis of our constellations the Dipper formed part of the larger constellation Ursa Major, the Great Bear. Interestingly, it also represented a bear to some indigenous North American cultures.
This will most likely be the last week that we will see Jupiter in the evening sky until late June. The giant planet now wallows in twilight and sets within an hour of sunset as the week begins. By next week Old Jove sets a bit more than half an hour after the Sun.
Venus is now very prominent in the pre-dawn sky, rising in the southeast at around 4:30 am. By 6:00 she is well above the tree line and can be easily picked out in the gathering twilight.
Mars accompanies Venus in the morning twilight, but he is pale by comparison to his dazzling neighbor. You will probably need binoculars if you try to find him in the brightening twilight, but he shouldn’t be too hard to see just south of his blazing companion.
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