Why are these the ‘Dog Days’ of Summer?

By Dave Ferreira

Usually a hot and dry period, late summer is often called the dog days (except maybe this year — instead of toasty hot dogs we have wet chilly dogs). It has to do with the brightest star in our sky, Sirius. Also known as the Dog Star, Sirius is the alpha star in the constellation Canis Major (translated: the Big Dog). For a period during the later summer, it appears near the sun at dawn.

One of our nearest and brightest stellar neighbors (only 8.6 light years distant), many cultures attached special significance or divine status to Sirius. In Egypt, the dawn rising of Sirius occurred just before the annual flooding of the Nile, an event critical to food growing in that desert region. The star’s rising marked the beginning of the Egyptian new year.

As Sirius came up with the summer sun, the ancients believed it added to the overall temperature of the hot weather and caused malignant emanations that bothered humans and animals. In fact, people thought it made environmental conditions just plain wiggy (supposedly this is where the word ‘starstruck’ originates). The book, ‘Sirius: Brightest Diamond in the Night Sky’, notes that classical Greeks felt the dog days made plants wilt, men weaken and women to become aroused. And from Wikipedia: Dog Days were popularly believed to be an evil time “when the seas boiled, wine turned sour, dogs grew mad, and all creatures became languid, causing to man burning fevers, hysterics, and phrensies,” according to Brady’s Clavis Calendarium, from 1813.  Sirius is actually an odd-couple binary star system: Sirius A is hotter, bluer and younger than our sun, and Sirius B is its tiny, burnt-out, white dwarf companion.