M28
NGC 6626
Object Data
- Catalog Designation
- M28
- Type
- GlobularCluster
- Constellation
- Sagittarius
- Magnitude
- 6.8
- Right Ascension
- 18h 24m 32.9s
- Declination
- -24° 52' 11.4"
- Distance
- 17,900 light-years
- Angular Size
- 11.2
Survey Image
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About M28
Description
M28 is a moderately bright globular cluster in Sagittarius, about 18,300 light-years from Earth. It contains several hundred thousand stars in a sphere about 60 light-years across. M28 was the second globular cluster (after M4) in which a millisecond pulsar was discovered.
Observing Tips
Located about 1 degree northwest of Lambda Sagittarii (Kaus Borealis), the top star of the Teapot. Easy to find but often overlooked in favor of nearby M22. In binoculars it appears as a small, round fuzzy spot. A 4-inch telescope shows a bright, concentrated glow. An 8-inch telescope at high magnification begins to resolve stars at the edges. Best observed from June through September.
History
Discovered by Charles Messier on July 27, 1764. He described it as a 'nebula without stars.' William Herschel was the first to resolve it into stars. In 1987, a millisecond pulsar (PSR B1821-24) was discovered in M28, rotating an astonishing 327 times per second.
Fun Facts
The millisecond pulsar in M28 rotates 327 times per second — its surface moves at about 16% the speed of light. M28 also contains 18 known RR Lyrae variable stars and a W Virginis type variable, making it useful for distance calibration studies.
Community Photos (1)
Credit: Credits: NASA, ESA, STScI, R. Buonanno (Universita di Roma Tor Vergata), K. Gebhardt (University of Texas at Austin), J. Grindlay (Harvard Universi.... License: Public domain. (Wikimedia Commons)
Skybred Feb 28, 2026
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