Sirius, Star of the Dog Days

Sirius, Star of the Dog Days

Sirius the Dog Star is the brightest star in the constellation Canis Major (the Great Dog). You can find it  on winter and spring evenings, as the faithful companion of  Orion the Hunter on his journey through the sky.

It is also the star of the dog days—the sweltering days of July and August, the hottest time of year in the northern Hemisphere.

Sirius is not only the brightest star in the night sky, it’s really a binary star—Sirius A and  Sirius B.

According to EarthSky,  Sirius A is about 8.6 light years from earth, and about 20 times brighter than our Sun. It is also hotter and more massive than the Sun.  Its companion is known as Sirius B, and is nicknamed  The Pup.

Sirius B  is a white dwarf, the hot, dense core of a star that was once like Sirius  A.  Sirius B is too faint to be seen without a telescope. The two stars orbit each other, a period of about 50 years.

Sirius has been observed since ancient times. Babylonian astronomers wrote of it in 300 B.C. Ancient Egyptians worshipped it.

This history of the stars and constellations states, “It is the only star known to us with absolute certitude in the Egyptian records — its hieroglyph, a dog, often appearing on the monuments and temple walls throughout the Nile country.  Its worship, chiefly in the north, did not commence till about 3285 B.C.”

The Egyptians based their calendar on the rising of  Sirius. They associated its reappearance with Isis and Osiris returning  from the underworld, signifying rebirth and renewal with the annual flooding of the Nile, and the beginning of a new year.

Arab astronomers called the constellation Al Kalb al Akbar, the Greater Dog, and  the star  Al Shira, the shining one. It has been speculated that the various names for the star we call Sirius  have a common Sanskrit origin–Surya–the shining one–the sun.

The name Sirius is derived from the Greek word seirios, which means shining or scorchingThe classical Greek and Roman belief was that the combination of the brightest light of the day (the sun) and the brightest star of night (Sirius) were responsible for the uncomfortable heat and humidity during the middle of the summer.

Two suns in the sky?  We know better now. But don’t get too smug about that. The scintillating light of Sirius is sometimes mistaken for a UFO!

Sirius makes its re-appearance in the predawn sky  late in August, marking the end of the dog days, and cooler days to come.


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Filed under: seasons, weather

Tags: dog days


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  • Ahhh... that's my kind of post, even if we argue a little about the spelling!

  • So glad you liked it. Seriously, since I posted this, we've had
    cooler than normal days. Furnace came on overnight 7-27!

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