WHAT DOES THAT REALLY MEAN?
These short newsletters generally reflect on topics that I think will be informative and insightful. Sometimes they’re meant to convey trends or offer helpful professional development. But in the midst of summer – and in the midst of a very active business year! — I thought it would be appropriate to take a break and send something lighter. When you’re done reading, take a random poll of colleagues and friends to see how many people know the origin of the term “the dog days of summer.”
The term “dog days” has an interesting origin that reaches back to the days of the Roman Empire.
Late July and early August tend to bring us the hottest and most sultry days of the year. This weather pattern holds fairly consistently for all of the mid-northern latitudes of Earth. Most of us call these the “dog days of summer.”
We realize today that this warm weather pattern occurs because it takes about a month for the vast oceans of Earth to distribute the energy that was absorbed when the Sun was most powerful in our skies (specifically June 21st, the longest day of the year and the first day of summer). But the Romans had not picked up on this connection. Instead, they looked for the cause in the skies that were overhead at the time.
They knew that during these summer days, two of the brightest objects shared the sky: the sun and the star Sirius. Sirius is the brightest star in our sky, and its Latin name means “the searing one.” In the summer it crosses overhead during the day. The Romans assumed that it must be Sirius, adding its heat and light to that of the sun, that was responsible for the oppressive heat of the season.
And what does that have to do with “dog days?” Well, Sirius is the most prominent star in the constellation Canis Major — the Big Dog. It has been known since Roman times as the “doq star.”
- – adapted from John Radzilowicz, director, Buhl Planetarium & Observatory
- – © Carnegie Museums of Pittsburgh Jul/Aug 2000