Summer Triangle

From Wikipedia, the free encyclopedia
  (Redirected from Summer triangle)
Jump to navigation Jump to search
Summer Triangle

The Summer Triangle is an astronomical asterism involving an imaginary triangle drawn on the northern hemisphere's celestial sphere, with its defining vertices at Altair, Deneb, and Vega, the brightest stars in the three constellations of Aquila, Cygnus, and Lyra, respectively.


The term was popularized by American author H. A. Rey and British astronomer Patrick Moore in the 1950s.[1] The name can be found in constellation guidebooks as far back as 1913.[2] The Austrian astronomer Oswald Thomas described these stars as Grosses Dreieck (Great Triangle) in the late 1920s and Sommerliches Dreieck (Summerly Triangle) in 1934. The asterism was remarked upon by Joseph Johann von Littrow, who described it as the "conspicuous triangle" in the text of his atlas (1866), and Johann Elert Bode connected the stars in a map in a book in 1816, although without label. These are the same stars recognized in the Chinese legend of The Cowherd and the Weaver Girl, a story dating back some 2,600 years, celebrated in the Qixi Festival. In the mid- to late-20th century, before inertial navigation systems and other electronic and mechanical equipment took their places in military aircraft, United States Air Force navigators referred to this asterism as the "Navigator's Triangle".[3]


Summer Triangle in the context of the starry night sky

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 to the East. In the autumn the summer triangle is visible in the evening to the West well until November. From the southern hemisphere it appears inverted, with Deneb below Altaïr, and low in the sky during the winter months.

The stars of the Summer Triangle[edit]

Name Constellation Apparent magnitude Luminosity
(× solar)
Spectral type Distance
(light years)
Radius (solar radius)
Vega Lyra 0.03 52 A0 25 2.36 to 2.82
Deneb Cygnus 1.25 70000 A2 3550 203 ± 17
Altair Aquila 0.77 10 A7 16.6 1.63 to 2.03

See also[edit]


  1. ^ Patrick Moore (20 October 1983). Patrick Moore's History of astronomy. Macdonald. ISBN 978-0-356-08607-1. 
  2. ^ Alice Mary Matlock Griffiths (1913), The Stars and Their Stories: A Book for Young People.
  3. ^ Lt. Col. William E. Hubert, USAF (Ret.) (December 1, 2006). "Chapter Eleven: "Triple Rated" Copilot, (Ugh)!". Pilot Here Or Pile It There: A Memoir. AuthorHouse. p. 115. ISBN 978-142595689-9. 

External links[edit]