2021, January 28: Sirius Rises at Sunset

Sirius in evening sky, January 2021
2021, January 28: An hour after sunset, Sirius appears low in the southeastern sky during late January.

January 28, 2021:  The sky brightest nighttime star, Sirius, rises at sunset from mid-northern latitudes to join winter’s brightest stars in their evening jaunts across the sky.

by Jeffrey L. Hunt

Sirius, the brightest star in the night sky, rises in the east-southeast at sunset from mid-northern latitudes during late January.  An hour later, the star is about 10° up in the southeastern sky.  It is likely twinkling wildly from the different temperatures and swirling winter air masses.

Sirius is commonly known as the “Dog Star,” the brightest star in Canis Major – the Greater Dog.  Procyon, the “Little Dog Star,” is to the upper left of Sirius. Betelgeuse – in Orion – is nearly above Sirius.  The three stars together are known as the Winter Triangle.

Writers suggest various shapes in the bright stars of the winter evening sky.  In addition to the Winter Triangle shape, I visualize the “Winter W.” Start at Procyon.  Then image the line goes to Sirius, Betelgeuse, Rigel, and Aldebaran.  It makes a letter “W,” like in the shape a four-year-old might write.

Through the night, the bright winter stars appear farther westward. Sirius seems to follow behind the bright stars in this section of the sky. Sirius is in the south, about 5 hours after sunset.  It sets in the west 4 hours before sunrise.

Unlike the planets, Sirius is not opposite the sun.  When a planet is at opposition, it rises at sunset and sets in the west at sunrise. 

Sirius is far below the ecliptic, where the sun and planets appear to move.  The result is that the star’s stay in the sky is shorter than a planet at opposition.

As the winter season progresses, Sirius appears higher in the southeastern sky each evening at an hour after sunset.  By mid-March, Sirius is in the southern sky after sunset.  A month later it is in the southwest.  By mid-May, Sirius makes its final appearance (heliacal setting) in the evening sky.  It sets with the sun (cosmic setting) by May’s end.  It rises with the sun (cosmic rising) during early July. Sirius reappears in the southeast before sunrise (heliacal rising) during mid-August.  It appears in the morning sky.  As the seasons progress, Sirius reappears in the evening sky after sunset next January.

Read more about the planets during January.


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Categories: Astronomy, Sky Watching

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