On this episode of Our Island Universe: Find out where we got the phrase The Dog Days of Summer
Shanil Virani, Director of the John C. Wells Planetarium Harrisonburg, VA.
Follow on Twitter as shanilv
Transcript:
As the calendar flips to August, here in the northern hemisphere, our days are long, lazy and HOT! Colloquially we refer to these sultry days as the “Dog Days of Summer”. Where does this saying come from? What is its connection to the stars?
Sirius, in the constellation Canis Major — the Big Dog — is the brightest star in our WINTER sky. Indeed, to our ancestors, seeing the nearby constellation, Orion the Hunter, rise near east as the sun set near west was the signal that winter was approaching in the northern hemisphere. So almost 6 months later, when they would observe the Sun and Sirius rising together near East, this indicated the arrival of the sweltering heat of late summer. Homer, in the Iliad, references the association of "Orion's dog”, Sirius, with oncoming heat, fevers and evil, in describing the approach of Achilles toward Troy:
Sirius rises late in the dark, liquid sky
On summer nights, star of stars,
Orion's Dog they call it, brightest
Of all, but an evil portent, bringing heat
And fevers to suffering humanity.
The Romans referred to this period as diēs caniculārēs - the “days of the dog star”.
To our ancestors, the sky was magical and full of patterns that they could decode but not explain. Today we know that our changing sky has to do with the Earth’s orbit around the Sun; and idea that would not be accepted until Galileo in the 17th century.