Sagitta the Arrow lies inside the Summer Triangle

Star chrt showing Summer Triangle, Delphinus, Vulpecula and Sagitta.
In the east on June, July and August evenings, you’ll find the large pattern of the Summer Triangle, made of 3 bright stars. And from a dark sky, you can also spot Sagitta the Arrow inside the triangle. Chart via Chelynne Campion/ EarthSky.

Even though the constellation of Sagitta the Arrow has been around since the 2nd century, it contains dim stars and is the third smallest of the 88 constellations. Sagitta the Arrow is sometimes related to Sagittarius the Archer, however, the two do not lie next to each other in the sky. Sagittarius lies low on the southern horizon during northern summer, while Sagitta is farther north. It almost appears as if Sagittarius has shot his arrow at Aquila the Eagle and missed, and the arrow (Sagitta) now lies on the other side of the Eagle from Sagittarius.

Locating Sagitta

Sagitta may be small and dim, but its position inside the Summer Triangle makes it easy to find. Sagitta and Vulpecula are the two constellations that take up residence between the constellations Cygnus the Swan, Lyra the Harp and Aquila the Eagle. Each of those constellations has one bright star that marks the corners of the Triangle: Cygnus’s star is Deneb, Lyra’s star is Vega, and Aquila’s star is Altair.

Sagitta lies north of Altair, inside the pointy end of the Summer Triangle. It consists of a line for the arrow’s shaft, and then it branches off on one end. Does it look like an arrow to you?

Stars of Sagitta the Arrow

Because of Sagitta’s small size, it contains few observing targets. The brightest star is Gamma Sagittae. At magnitude 3.5, it lies 274 light-years away. About three degrees west is Delta Sagittae, a magnitude 3.8 star lying 448 light-years away. Then just a bit less than two degrees west of Delta are two stars both at magnitude 4.3. The one slightly north is Alpha Sagittae and the one slightly south is Beta Sagittae. Alpha lies 473 light-years from Earth, while Beta lies 467 light-years away from us.

White star chart with black dots denoting the small arrow.
The stars of Sagitta the Arrow. Image via IAU.

Sagitta’s Messier object

The one notable deep-sky target in Sagitta is also its only Messier object: the globular cluster M71. You can find M71 halfway between the stars Gamma and Delta. At magnitude 6.1, you’ll need binoculars or a telescope to spot it. Because of M71’s appearance, astronomers long thought that it was an open cluster with a rather dense center. Astronomers now believe it’s a young globular cluster that is smaller and looser than typical globular clusters. M71 lies about 13,000 light-years distant.

Bottom line: Sagitta the Arrow is a dim constellation that lies inside the Summer Triangle. It contains one Messier object, a small globular cluster.

August 1, 2022

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Kelly Kizer Whitt

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