Friday, July 3, 2015

Tonight's Sky for July 3: The Dog Days Begin


It's roughly two weeks from the start of summer for us living in the Northern Hemisphere, which means that the heat is on, but it has nothing to do with a certain Dog Star. In the time of the Ancient Egypt, the people noticed that the hottest days of the year correspond to a point in time wherein Sirius, brightest star in the sky, is very close to the Sun, so close that Sirius lent its heat to the Sun and helped make summer, particularly the 40 days between July 3 and August 10, the hottest month of the year.

Well, we now know that Sirius is 8.6 light years distant and plays no part in Earthly weather. Still, this is an interesting space history lesson and the explanation for a common phrase whose origin is unknown by many of the people who actually use it!

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