Dog Days of Summer

(Canis Major in the Morning Sky)

Did you know that the dog days of summer have nothing to do with dogs and everything to do with the stars in the heavens.

"The brightest of the stars in Canis Major (the big dog) is Sirius, which also happens to be the brightest star in the night sky. In fact, it is so bright that the ancient Romans thought that the earth received heat from it. Look for it in the southern sky (viewed from northern latitudes) during January.
In the summer, however, Sirius, the “dog star,” rises and sets with the sun. During late July Sirius is in conjunction with the sun, and the ancients believed that its heat added to the heat of the sun, creating a stretch of hot and sultry weather. They named this period of time, from 20 days before the conjunction to 20 days after, “dog days” after the dog star.
The conjunction of Sirius with the sun varies somewhat with latitude. And the “precession of the equinoxes” (a gradual drifting of the constellations over time) means that the constellations today are not in exactly the same place in the sky as they were in ancient Rome. Today, dog days occur during the period between July 3 and August 11. Although it is certainly the warmest period of the summer, the heat is not due to the added radiation from a far-away star, regardless of its brightness. No, the heat of summer is a direct result of the earth's tilt."
Jerry Wilson