Starwatch: Arrow-shaped constellation Sagitta stands out against dark summer skies

This week's night-sky challenge turns to one of the smaller constellations of the northern summer: Sagitta, the arrow. Made up of only a handful of dim stars, it is nonetheless fairly easy to pick out thanks to its unmistakable arrow-like outline.

According to the accompanying observation chart, the view is oriented toward the zenith while facing south from London at 22:30 BST on Monday. Sagitta sits roughly midway along an imaginary line drawn between the bright stars Vega and Altair, which together with Deneb form the well-known summer triangle.

An ancient constellation

Despite ranking as only the third-smallest constellation in the entire sky, Sagitta has been documented since ancient times. It appeared on the list of 48 constellations compiled by the 2nd-century astronomer Ptolemy in his work The Almagest.

Greek mythology offers several possible origin stories for the arrow. Some accounts link it to the arrow Hercules used to kill the eagle that tormented Prometheus, while others associate it with one of Cupid's famous arrows.

The constellation is also visible from the southern hemisphere during August, though observers there will see it positioned lower in the northern part of the sky than viewers in the UK do.