07/16/2015 – Ephemeris – The Summer Triangle is the sign of the season

Ephemeris for Thursday, July 16th.  Today the Sun will be up for 15 hours and 12 minutes, setting at 9:25.   The Moon, 1 day past new, will set at 9:32 this evening, and tomorrow the Sun will rise at 6:13.

We’re almost a month into summer, and the asterism or informal constellation called the Summer Triangle can be seen midway up the sky in the east as it gets dark.  Highest of the three bright stars is Vega in the constellation Lyra the harp, whose body is seen in a narrow parallelogram nearby.  The second star of the triangle is Deneb lower and left of Vega, It appears dimmer than Vega because it is by far the most distant of the three.  The third star of the Summer Triangle is seen farther below and a right of Vega.  It is Altair in Aquila the eagle, and the closest.  Altair is 16.5 light years away, Vega is 27 light years while Deneb is so far away that it’s distance is in some doubt and may be 2,600 light years away.

Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Summer Triangle. Created using Stellarium.