Do you know where the term “dog says of summer” originated? Sam and Elsa here. When mom said we could do a post about the Dog Days of Summer, it set our tails-a-waggin’. Something about dogs?…oh heck yes! Put us in, coach.
Follow the belt of Orion to find
Sam and Elsa’s Star Sirius. Credit: Starry Night Software
Typically those hot, sultry days in summer are referred to as “dog days” or “dog days of summer.” Visible from anywhere on Earth, Sirius is part of the constellation Canis Major otherwise known as the Greater Dog. Dog? Hmm, why they didn’t just call it Sam and Elsa’s star is still a mystery to us. Perhaps it’s due in part to the ancient history we learned. Right now you see ‘our star’ as it ascends in the east before dawn on late summer mornings. The simple answer is because the hottest/most humid days of summer are associated with Sirius (aka the “Dog Star”) because it was the brightest star in the constellation Canis Major.
Now for some astronomic history…first from the Egyptians. The period following the heliacal rise (that period of less than a year when it had not been visible) of Sirius when the constellation becomes visible just above the eastern horizon before sunrise generally arrives around July 19th and ends around the last week of August. This timeframe roughly corresponded with the annual flooding of the Nile River.
Not to be outdone on all things Sirius, ancient Romans believed it radiated extra heat toward the Earth. During the summer when Sirius rises and sets with the Sun, they were convinced the added, additional heat to the Sun’s heat caused hotter summer temperatures.
For the ancient Romans, the dog days of summer period was from about July 24 to around August 24. Over time, the constellations have drifted somewhat and today, The Old Farmer’s Almanac lists the dog days of summer to be from July 3 until August 11.
Although “dog days” are usually the hottest of the summer, they really don’t have anything to do with either dogs or the star Sirius. Actually it is Earth’s tilt that explains why these days tend to be the hottest during summer.
The Earth’s tilt this time of year causes the sun’s light to hit the Northern Hemisphere at a more direct angle and, accordingly for a longer period of time throughout the day. This means longer, hotter days during the summer. While Sirius is the brightest proper star in the night sky, it still is 8.7 light-years (8.23×1013 km) away and effectively has no effect on Earth’s weather or temperature.
Yet the effects of summer heat and rainfall patterns are real and variations occur by latitude and location according to many factors. Although London is farther north, Calgary has a milder climate from the presence of the sea and the warm Gulf Stream current. One medical institution has reported a connection between Finland’s dog days and an increased risk of infection in deep surgery wounds, though that research is unverified.
So there you have it as to some of the why’s and the what for’s about the dog days of summer. All that abbreviated history aside, us Knuckleheads tend to be lazy during these pizza-oven hot days (mid 90’s for the past few days). We enjoy early morning walks, and laze about working on our napping form as demonstrated by Sunday’s ‘howliday,’ National Dog Day. Mostly we are over these dog days and are excitedly awaiting for Indian Summer to arrive. How have your dog days been?
Live, love, bark! 🐾