The “dog days of summer” are here. Climatologically speaking, we are smack in the middle of the hottest time of the year in Northwest PA. When you hear the term “dog days of summer,” it refers to the period of time from July 3rd through August 11th. Usually the hottest weather occurs within this time period, but what you may not know is the term “dog days of summer” has nothing to do with actual canines.
The term “dog days of summer” has deep roots and dates back thousands of years and it all has to do with the stars, in particular the star “Sirius” which is also known as the dog star. The movement of the stars has changed over time, and this presents a bit of a conundrum. Back in ancient times, the movement of the stars was like following a calendar like we do today. The movement of the stars helped mark seasons and was particularly useful for navigation by land and sea. One of the problems now is the fact that the lunar calendar has only 355 days, while the solar calendar has 365 days. The 10 day gap between the two calendars can throw the seasons off. In other words, the seasons would be occurring over different lunar months over time, which means the “dog days” would not correspond correctly.
Additionally, latitude plays a big role for when the “dog days” occur. The rotation of Earth is another reason that causes the “dog days” to no longer correspond to ancient times. As the earth rotates, it wobbles and can change the position of the stars, depending on how it is wobbling. This wobble is called axial precession. The Earth completes a full cycle of axial precession once every 26,000 years. The change in both the rotation and axial precession of the Earth has resulted in the position of the stars being different compared to the position of the stars in ancient times.
While you are enjoying the “dog days” with your canine companions, it actually has nothing to do with them. The origin of the term can be traced back to the stars.
As we continue through the hottest part of the year, it is important to remember to never leave your pets in the car during hot weather for any length of time, and make sure they have plenty of water as well.