The most prominent star patterns are sometimes not constellations at all. Take the summer triangle. It is a prominent pattern of stars that rides high in the sky at this time of year in the northern hemisphere. The shape is composed of Deneb in Cygnus, the swan; Vega in Lyra, the lyre; and Altair in Aquila, the eagle. All three stars give out a blue-white light.
It has been called the summer triangle in the west since at least 1913. Before that, the pattern was marked on 19th-century star charts. The term was popularised by the British astronomer Patrick Moore in the latter half of the 20th century. However, the triplet of stars has long been recognised by other cultures, featuring in, for example, a Chinese folk story about a cowherd and a weaver girl.
Patterns of stars that are not recognised as marking out traditional constellations are called asterisms. Other examples include “the teapot”, which is the central portion of stars in Sagittarius, the archer; and the plough, which is composed of a subset of stars from the constellation Ursa Major, the great bear. From the southern hemisphere, the triangle of stars can be seen by looking north.
