January 28, 2022: Within a few minutes, Sirius rises at sunset this evening. About two hours after sundown, find it in the southeastern sky with the other bright stars of Winter.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 7:07 a.m. CST; Sunset, 5:01 p.m. CST. Check local sources for sunrise and sunset times for your location.
The evening’s brightest star, Sirius, rises within a few minutes of sunset at the mid-northern latitudes this evening. Two hours after sunset, find it low in the southeast, likely twinkling wildly from the turbulent chilled air of the winter’s evening.
Also known as the “Dog Star,” Sirius is the brightest star in Canis Major, the Greater Dog. Along with Procyon – part of Canis Minor – and Betelgeuse, the three stars make the Winter Triangle.
Sirius is also known as the “Nile Star.” In ancient Egypt, it made its first morning appearance at the time of the annual flooding of the Nile River. Artifacts suggest that Egyptian calendars may have been based on moon phases, the annual flooding of the river, and the annual predawn appearance of Sirius (source). And there is some indication that specific calendars were used in different Egyptian eras.
In these ancient times, Sirius made its first theoretical morning appearance during July. The date changed over the years because of a slight wobbling of Earth from gravitational forces of the sun and the moon. This slightly changes the positions of the stars in the celestial coordinate system.
The actual date of the first appearance is affected by local atmospheric conditions. Long spells of thick clouds or clouds near the horizon affect the observations. While the star might be theoretically visible to the unaided eye, fog, haze, clouds, or other atmospheric effects can delay the first sighting.
After the helical rising, Sirius is higher in the sky each morning before sunrise and farther westward. It follows the annual westward migration of the stars, from Earth’s revolution around the sun. By mid-October, it rises around midnight and appears in the south before sunrise. A month later it rises about two hours earlier.
Canis Major and Canis Minor are sometime portrayed as Orion’s hunting dogs. They follow him across the sky. Procyon’s name is sometimes translated as “before the dog,” as it rises about 25 minutes before Sirius from the mid-northern latitudes. As 2021 closed, it appeared above the horizon before 7 p.m.
Sirius is in the evening sky, until it disappears into bright twilight in the western sky after sunset during mid-May. It sets with the sun on May 27. During the summer months, Sirius is in the sky during the daytime. It reappears in the morning sky before sunrise during mid-August, about the time of the Perseid meteor shower each year, from the mid-northern latitudes.
After the Alpha Centauri star system and some other much dimmer stars, Sirius is the seventh nearest star to our solar system.
The brightest star is over eight light years away. Procyon is about three light years more distant. Betelgeuse, along with Rigel, are the most intrinsically bright stars in the night sky. Betelgeuse is distinctly rosy in color, while Rigel is sapphire-white.
Look for Sirius in the southeast as it follows the bright stars of winter westward.
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