Starwatch for July 2021

Written by on July 19, 2021

Hello! I’m Karl Hricko of United Astronomy Clubs of NJ and the National Space Society, bringing you the July starwatch for WNTI.ORG

Summer is here! And so are the Dog Days of summer. We normally think of them as being hot and humid days. For the Egyptians, these days are when the Nile floods and provides a good planting season. For the Greeks and Romans these are days of hot weather and drought. So why is it called “Dog Days”? It all has to do with Astronomy.

Dog Star refers to a bright star called “Sirius” located in the constellation Canis Major, or the Great Dog. It marked the beginning of the Dog Days, when it rises at predawn.

The ancient Egyptians called   this star “Sothis”, or ”Isis” the goddess who was thought to have brought prosperity by the flooding of the Nile. The ancient Greeks named it “Seirios”, meaning the scorcher or sparkling star. They believed it, along with the Sun, caused the hot weather. The Romans Latinized it to Sirius, and also termed it the Dog Star, or “Deis Canulares”.

Besides having a Big Dog romping through the heavens this month, we also have godly planets rolling across our night sky.

At dusk, you can see Mars and Venus seeming to combine together at midmonth in Cancer, looking west. Waxing crescent Moon will be off to their right. At dawn in the southwest, Jupiter is high in the sky in Aquarius, while Saturn is lower to the right in Capricornus. The full Moon moves in a path below them at the end of the month. So summer not only brings the beginning of Dog Days, but also the rising of a Dog Star.


Until our next Starwatch -Don’t forget to check out … What’s up in the night sky

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