If you live in the Northern Hemisphere, there comes a period during July and early August when the weather is hot and the days are long. Often during this time, people will talk about the Dog Days of summer.
Perhaps you’ve noticed that your dog becomes a bit more sluggish during this hot period of the summer, or that they are panting significantly more during their daily walks? Well, those actually have nothing to do with the phrase.
If you’re scratching your head like you’ve got fleas, worry not. For an explanation of why we say the Dog Days of summer, you need to take your eyes of Fido and look up.
Why Do We Say the Dog Days of Summer?
During the summer months, the sun shares the sky with the star Sirius. Called the Dog Star, Sirius is the brightest star in the night sky and is part of the constellation Canis Major, which translates into “Greater Dog.”
The term “Dog Days” actually comes from the Ancient Romans, who called those hot humid days “diēs caniculārēs” or “Dog Days.” The civilization believed Sirius’ bright light radiated extra heat toward Earth, making the days hotter. They deemed the Dog Days to begin in late July, the time when Sirius begins to appear just before sunrise.
This galactic occurrence has even made its way into ancient literature, helping illustrate how significant the star was. In the Iliad, Homer refers to Sirius as Orion’s dog rising. The star came to be associated with war and disaster, which explains why the Ancient Romans believed this time of year could bring about fever, disease, and other types of catastrophe.
When Are the Dog Days of Summer?
For the Ancient Romans, the Dog Days took place from approximately July 24th to August 24th. However, the constellations have shifted since those ancient days, and The Old Farmer’s Almanac says that these days last from July 3rd until August 11th.
Today, however, the Dog Days refer less to an actual set time period. Instead, people tend to use the phrase more generally, as a way to describe the long, hot days associated with summer.
Furthermore, over the years it has become more common for people to assume that the Dog Days are related to man’s best friend. Of course, you’re still likely to find your dog lounging in the shade during this time of year. It IS hot out, after all.
Why Are the Days Hotter During Summer?
With Sirius located 8.611 light years away from Earth, its bright light doesn’t have an impact on the planet’s temperatures. However, the solar system does have a lot to do with the intense heat we experience during this part of the season.
During summertime in the Northern Hemisphere, the sun’s light is hits the planet at a more direct angle due to the tilt of the Earth. This direct light is also hitting Earth for a longer period of time, making summer’s days longer and hotter.
For this reason, in the Southern Hemisphere, the Dog Days of the summer run from late January to early March. This is when these countries are in the sun’s direct path, meaning that they’re soaking up the sun while those in the Northern Hemisphere are bundling up.
Are The Dog Days Really The Hottest?
So, are these Dog Days truly the hottest of the year. The answer depends on where you’re located. Contingent on your latitude, the hottest days in your region will vary from those in other countries.
The answer also depends on where Earth is on its axis. The planet doesn’t rotate in a steady circle, causing the location of the stars in the night sky to shift as Earth wobbles on its axis. This is also why the Dog Days of the present vary from those that the Ancient Romans first observed thousands of years ago.