Saturday, May 30, 2009
The Summer Triangle is an an imaginary triangle drawn on the northern hemisphere's celestial sphere, with its defining vertices at Altair, Deneb, and Vega. This triangle connects the constellations of Aquila, Cygnus, and Lyra.
Near midnight the Summer Triangle lies virtually overhead at mid-northern latitudes during the summer months, but can also be seen during spring in the early morning. In the autumn the summer triangle is visible in the evening well until November. From the southern hemisphere it appears upside down and low in the sky during the winter months.
Name / Constellation
Vega / Lyra
Deneb / Cygnus
Altair / Aquila
Altair is the brightest star in the constellation Aquila and the twelfth brightest star in the night sky with an apparent visual magnitude of 0.77 .
Deneb is the brightest star in the constellation Cygnus and one of the vertices of the Summer Triangle. It is the 19th brightest star in the night sky, with an apparent magnitude of 1.25. A white supergiant, Deneb is also one of the most luminous stars known.
Vega is the brightest star in the constellation Lyra, the fifth brightest star in the night sky and the second brightest star in the northern celestial hemisphere, after Arcturus. It is a relatively nearby star at only 25 light-years from Earth, and, together with Arcturus and Sirius, one of the most luminous stars in the Sun's neighborhood.