The Summer Triangle is a Northern Hemisphere asterism (stars of similar brightness recognized in a distinctive shape). Unlike many other asterisms, the Summer Triangle is actually a combination of stars from three separate constellations: Deneb, the brightest star in the constellation Cygnus the Swan; Vega, the brightest star in the constellation Lyra, the Harp; and Altair, the brightest star in the constellation Aquila, the eagle.
From mid-northern latitudes, the Summer Triangle appears virtually overhead around solar midnight during summer. It is also visible in the eastern sky in early mornings during spring. In autumn and winter evenings, the Triangle is visible in the western sky until January.