Saturday July 12, 2025

The Summer Triangle (all night)

After dusk in mid-July, the first stars to appear in the darkening eastern sky are Vega, Deneb, and Altair. Those three bright, white stars form the Summer Triangle asterism - an annual feature of the summer sky that remains visible until the end of December! The highest and most easterly of the trio is Vega, in Lyra. At magnitude 0.03, Vega is the brightest star in the summer sky, mainly due to its relative proximity. It's only 25 light-years away from the sun. Magnitude 0.75 Altair, in Aquila, occupies the lower right (southern) corner of the triangle. Altair is 17 light-years from the sun. By contrast, Deneb, which shines somewhat less brightly at magnitude 1.25, is a staggering 2,600 light- years away from us; but it shines so brightly because of its greater intrinsic luminosity. Once the bright moon departs next week, watch
for the Milky Way passing between Vega and Altair and through Deneb.

(Data courtesy of Starry Night)
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* Origin: CJ's Place, Orange City FL > cjsplace.thruhere.net (21:2/156)