M28

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.

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.

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.