Judy Isacoff: Dog Star appears, preceding the sun


In popular parlance, the hot and humid days of summer are known as the "dog days," embodied by a panting, sweating, lethargic dog as stand-in for the human experience. The backstory is intriguing.

Thousands of years ago, Greek and Roman lore identified the first week of July through mid-August as the Dog Days, based on an approximation of the time that Sirius the Dog Star was in conjunction with the sun. It was posited that the combined forces of the sun and the brightest star of the night sky were responsible for the exceptional heat. Relief was at hand when Sirius emerged from its alignment with the sun. And so it is now, in mid-August, that the beautiful Dog Star is close above the east-southeast skyline at dawn, preceding the rising sun. Tomorrow morning, Sirius rises at 4:53 and the sun at 6:04. When figuring your observing times, adjust for hilly terrain.

Joe Rao, a favorite among astronomy writers, relates that in 70 B.C. the astronomer Geminus wrote, "It is generally believed that Sirius produces the heat of the Dog Days, but this is an error, for the star merely marks a season of the year when the sun's heat is the greatest." For most of us, Sirius is best known as a distant sun of winter nights, associated with Orion the Hunter.

Look to the east-northeast at dawn all week, but especially tomorrow, to behold a dazzling planetary dance to the left of Sirius the Dog and other familiar winter constellations prominent in the east-southeast.

Planets Venus and Jupiter nearly touch tomorrow, best seen by 5:30 a.m. Venus is the brilliant Morning Star with less bright Jupiter on the right. To Jupiter's right find dimmer Procyon, the Little Dog, and further right, bright Sirius. Each morning finds Venus lower in the sky and Jupiter higher above the horizon. A crescent moon adds to the charming sequence from midweek to week's end.

To contact Judy Isacoff, go to: www.naturesturn.org


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