英文词源
- dog days (n.)
- 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.
中文词源
天狼星的口语叫法，当天狼星升起的时候（7，8月份），也就是一年中最热的时候。
该词的英语词源请访问趣词词源英文版：dog days 词源，dog days 含义。
古罗马人认为，在7月中至8月底这一时节，犬星即天狼星（Dog Star，即Sirius）与太阳同时起落，给太阳增添了热量，无异于助烈日肆虐，从而造成异常酷热的天气。因此此段酷暑期为Dog Star Days，后来简称为dog days，相当于汉语的“三伏天”。虽然后人发现dog days的酷热与Dog Star无甚关联，但是dog days却一直沿用了下来。
