Messier 21

Messier 21 (M21) is a open cluster in the constellation Sagittarius, with an apparent magnitude of 5.9. It is about 3,930 light-years away.

Finder chart for Messier 21 in the constellation Sagittarius
Messier 21 (circled) in Sagittarius. Pink symbols mark Messier objects.
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Facts

CatalogMessier 21 (M21)
Typeopen cluster
ConstellationSagittarius
Apparent magnitude5.9
Distanceabout 3,930 light-years
Right ascension18 h 4.2 min
Declination−22.49°
Best monthAugust (at about 9 pm)

Sources: star positions, magnitudes and colors from the Yale Bright Star Catalogue; constellation boundaries and star names from the IAU; areas and distances from Wikidata; stick figures by M. van der Sluys. How the maps are made.

How to find M21

M21 is in Sagittarius. From 40° N it is highest in the south in August evenings, about 28° up. From 35° S it reaches about 77° in the north. Binoculars show it under a dark sky; a small telescope shows more detail.

Sagittarius constellation →

Other Messier objects in Sagittarius

Lagoon Nebula (M8)Omega Nebula (M17)Messier 18 (M18)Trifid Nebula (M20)Messier 22 (M22)Messier 23 (M23)Sagittarius Star Cloud (M24)Messier 25 (M25)Messier 28 (M28)Messier 54 (M54)Messier 55 (M55)Messier 69 (M69)Messier 70 (M70)Messier 75 (M75)

The Messier catalog →

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