Sagitta

A tiny constellation, actually the third smallest of all the constellations after Crux and Equuleus, Sagitta lies sandwiched between Vulpecula the Fox and Aquila the Eagle on the band of the Milky Way. Though lacking in bright stars, the constellation's distinctive arrow shape, and its location directly northward of brilliant Altair in Aquila, makes it relatively easy to locate in a clear summer sky in the northern hemisphere.

Sagitta's unmistakable thin and pointed shape means that various cultures have known it as the 'Arrow' since ancient times. It is unclear whether it plays any larger part in the mythology of the sky, though some sources suggest that it may represent one of the poisoned arrows of Hercules, whose own constellation lies directly to the west. Despite the similarity of names, Sagitta does not appear to have any direct connection with Sagittarius, the constellation of the Archer, which lies somewhat to the south along the Milky Way.

Stars

The star marking the tip of the Arrow is also the constellation's brightest: a red giant designated Gamma Sagittae. With a visual magnitude of just +3.5 it is far from a bright star, but nonetheless it outshines all other stars in the constellation. At a distance of just over 250 light years, it is also the closest of Sagitta's four main stars to the Solar System.

The angle of the Arrow's shaft has it flying from the southwest, and that shaft is formed by a line from Gamma Sagittae to another red giant star, the pulsating variable Delta Sagittae. From there the shape splits, with two fainter stars representing the flights of the Arrow. These two stars are designated Alpha and Beta Sagittae (in a break with the convention that normally reserves 'Alpha' for the brightest of a constellation's stars).

Alpha Sagittae is notable as the only one of Sagitta's stars to carry a traditional name: Sham, again meaning 'Arrow', from the Arabic name for the entire constellation. Sham is a G-type supergiant star, very distant from the Solar System at a range of some 430 light years.

Star Clusters

Sagitta is not rich in deep sky objects, but an important exception is the cluster known as M71. This is a globular star cluster, falling close to the line marking the Arrow's 'shaft' (that is from Gamma to Delta Sagittae). This relatively loose ball of old stars falls within the plane of the Milky Way, and at a distance of some 12,700 light years from Earth, it lies far, far beyond the four stars that define the constellation's shape.