The "Dog Days" of summer is the name for the most sultry period of summer. While the exact dates are someone frivolous, it's typically considered to be July 3 to August 11, or the hottest part of the year.
There are lots of myths surrounding the "Dog Days" of summer. Everything from snakes go blind, fish won't bite and even wounds won't heal during the Dog Days.
As with many of our catchy terms, this too comes from ancient observers. The term comes from the constellation Canis Major or "Large Dog." Located in the constellation is a bright star named Sirius, which is known as the dog star.
With the exception of the sun, Sirius is the brightest star that is visible from earth. Early astronomers would track the star throughout the year, but noticed by mid-summer it would rise and fall with the sun and get lost in the daytime light.
Since they knew the bright star was in the sky the same time as the sun, the early astronomers figured it must be adding extra heat to produce the hottest months of the year. Not quite.
While it's bright, Sirius can't compare to the sun. It's about a half a million times farther away from the earth than the sun.
Sun, Distance to Earth = 92,960,000 miles
Sirius, Distance to Earth: 8.611 light years