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So-called for the dog star SIRIUS,
brightly visible just before the sun
in the eastern sky in mid July
Thought to contribute
to the heat. |
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The "dog days" of summer are upon us
— the hottest, |
stickiest time of the year. |
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The dog days get their name from
the dog star, Sirius. At this time of year, Sirius appears quite near the Sun in our sky.
It's also the brightest star in Earth's night sky, so ancient skywatchers thought the heat
from Sirius and the Sun combined to produce the year's hottest weather. Sirius IS hotter
than the Sun, but it's also 50 TRILLION miles from Earth. At such a great distance, Sirius
doesn't do anything to warm our planet.
Because it's so bright, and because of the time of year it first appeared in the morning
sky, Sirius played a crucial role in daily life in ancient Egypt. Its first appearance in
the morning twilight marked the beginning of the Egyptian year. It also heralded the
annual flooding of the Nile River, which deposited fertile soil in the Nile Valley.
If Sirius looked bright and clear on its first morning appearance, Egyptians expected an
abundant harvest. But if it looked red and dusky, they expected a poor harvest.
Three thousand years ago, this first pre—dawn appearance occurred in early July.
Today, though, it happens several weeks later. |
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