06/25/2025
Temperatures are SCORCHING this week—we are just short of the period of what many people call the "Dog Days of Summer" or hottest days of the year. On average, these days lie shortly after the summer solstice—when the Sun's intense summer rays beam right over the Northern Hemisphere!
The saying "Dog Days of Summer" likely has roots in ancient Egypt. The Egyptians were well-versed in math and astronomy. They paid close attention to the sky. One celestial object that was extremely important to them was the brightest star in the nighttime sky: Sirius. To them, Sirius' name was Sopdet, the Egyptian god of fertility and renewal. The days when Sirius/Sopdet rose just before the Sun in their sky matched up almost perfectly with the annual flooding of the Nile River, bringing in fertile silt they used for agriculture. They believed Sopdet brought forth this annual flooding. But Sopdet is not depicted as a dog in Egyptian art and literature, so it doesn't yet explain where the "dog days of summer" saying came from…
Sirius wasn't associated with a dog until the Greeks came around and started interacting with the Egyptians. Through trade and eventual occupation—the Greeks' mythology and astronomy were likely influenced by the Egyptians. The Greeks might have observed how the Egyptians held Sirius sacred—believing it affected the natural world—so it would be no surprise if the Greeks inherited this belief. To the Greeks, though, Sirius did not herald flood and fertility. In Ancient Greece, the period following the summer solstice brought scorching heat and drought. The Greeks believed that—because Sirius is so bright—its light, combined with the Sun's light, must have been responsible for the tremendous heat that bore down on them following the summer solstice—infact, the Greek name for Sirius was "Seirios", meaning "Scorching". The Greeks referred to this period as simply being the time that the star Sirius/Seirios was prominent—"the time of Seirios"—but they were the first to envision Sirius/Seirios as the dog star in their constellation "Kyon"—later called "Canis Major" by the Romans—which, according to Greek Mythology, was a hunting dog of Orion. Later, when the Romans came along and adopted/adapted much of Greek culture, they started calling this time of year "dies caniculares" or "days of the dog (star)", from which evolved today's phrase "Dog Days of Summer."
Today, we know that no star in our nighttime sky contributes any measurable amount of heat to our days. It's solely coincidental that the hottest days of the year occur when Sirius and the Sun share the sky. But that isn't true for everywhere on Earth—our upside-down friends in Australia are currently experiencing winter, despite Sirius rising shortly before the Sun in their sky as well.
Hopefully, this cool fact was refreshing on these hot summer day!
