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dog days,name for the most sultry period of summer, from about July 3 to Aug. 11. Named in early times by observers in countries bordering the Mediterranean, the period was reckoned as extending from 20 days before to 20 days after the conjunctionconjunction,
in astronomy, alignment of two celestial bodies as seen from the earth. Conjunction of the moon and the planets is often determined by reference to the sun.
..... Click the link for more information. of Sirius (the dog star) and the sun. In the latitude of the Mediterranean region this period coincided with hot days that were plagued with disease and discomfort. The time of conjunction varies with difference in latitude, and because of the precession of the equinoxesprecession of the equinoxes,
westward motion of the equinoxes along the ecliptic. This motion was first noted by Hipparchus c.120 B.C. The precession is due to the gravitational attraction of the moon and sun on the equatorial bulge of the earth, which causes the earth's axis to
..... Click the link for more information. it changes gradually over long periods in all latitudes.
Dog Days(religion, spiritualism, and occult)
Dog days are a 40-day period, usually given as July 3 to August 11, that is regarded as being the hottest time of the year. This period was originally calculated from the heliacal rising of Sirius, the Dog Star, after which dog days received its name.
dog days[′dȯg ‚dāz]
Although there are many different ways of calculating which days in any given year are the dog days, and how long they last, it is impossible to be precise. Nowadays it is generally assumed that they fall between July 3 and August 11—slightly later than they occurred in ancient times.
Because of their association with the Dog Star, various beliefs have sprung up involving the behavior of dogs during this period. In the 16th century it was believed that dogs went mad during the Dog Star season. Another name for this time of year, the canicular days, comes from the Latin word canis meaning "dog."
BkDays-1864, vol. II, p. 5
DictDays-1988, p. 32
DictFolkMyth-1984, p. 918
OxYear-1999, p. 595