S: http://news.nationalgeographic.com/2015/07/150710-dog-days-summer-sirius-star-astronomy-weather-language/ (last access: 31 December 2015); http://www.accuweather.com/en/weather-video/video-dog-days-of-summer/1076971271001 (last access: 31 December 2015).
N: 1. 1530s, from Latin dies caniculares, from Greek; so called because they occur around the time of the heliacal rising of Sirius, the Dog Star (kyon seirios). Noted as the hottest and most unwholesome time of the year; usually July 3 to Aug. 11, but variously calculated, depending on latitude and on whether the greater Dog-star (Sirius) or the lesser one (Procyon) is reckoned.
The heliacal rising of Sirius has shifted down the calendar with the precession of the equinoxes; in ancient Egypt c. 3000 B.C.E. it coincided with the summer solstice, which also was the new year and the beginning of the inundation of the Nile. The “dog” association apparently began here (the star’s hieroglyph was a dog), but the reasons for it are obscure.
2. Many people today use the phrase to mean something like that—but originally, the phrase actually had nothing to do with dogs, or even with the lazy days of summer. Instead, it turns out, the dog days refer to the dog star, Sirius, and its position in the heavens.
To the Greeks and Romans, the “dog days” occurred around the day when Sirius appeared to rise just before the sun, in late July. They referred to these days as the hottest time of the year, a period that could bring fever, or even catastrophe.
“If you go back even as far as Homer, The Iliad, it’s referring to Sirius as Orion’s dog rising, and it describes the star as being associated with war and disaster,” said Jay B. Holberg, author of Sirius: Brightest Diamond in the Night Sky and senior research scientist at the University of Arizona Lunar & Planetary Laboratory. “All throughout Greek and Roman literature, you found these things.”
The phrase “dog days” was translated from Latin to English about 500 years ago. Since then, it has taken on new meanings.
3. “Our Earth is like a spinning top,” said Bradley Schaefer, professor of physics and astronomy at Louisiana State University. “If you toss it onto a table, after it slows down … the pointing direction of the top will slowly go around in circles.” Similarly to a top, “the Earth’s rotation is kind of wobbling around.”
“The calendar is fixed according to certain events, but the stars have shifted according to the way that the Earth wobbles,” said Larry Ciupik, astronomer at Adler Planetarium and director of the Doane Observatory. “So in about 50-some years, the sky shifts about one degree.”
This means that the dog days of ancient Greece aren’t the dog days of today. What it also means is that several millennia from now, this astrological event won’t even occur during the summer.
“In 26,000 years, the dog days would completely move all around the sky,” said Schaefer. “Roughly 13,000 years from now, Sirius will be rising with the sun in mid-winter.”
4. Cultural Interrelation: We can mention Dog Days (ドッグデイズ Doggu Deizu?, stylized as DOG DAYS) a Japanese fantasy anime television series created by Masaki Tsuzuki in 2011.
S: 1. OED – http://www.etymonline.com/index.php?term=dog+days (last access: 31 December 2015). 2 & 3. http://news.nationalgeographic.com/2015/07/150710-dog-days-summer-sirius-star-astronomy-weather-language/ (last access: 31 December 2015). 4. https://en.wikipedia.org/wiki/Dog_Days_(anime) (last access: 31 December 2015).