101 Must-See Cosmic Objects: Omega Centauri

The most glorious of all globular clusters is Omega Centauri. (NGC 5139 is its more mundane designation.) It’s the 24th-brightest “star” in Centaurus, which is the ninth largest of 88 constellations. It was noted in Ptolemy’s Almagest in A.D. 150 and designated Omega (ω) by Johann Bayer in his 1603 Uranometria. Edmond Halley is credited for first noting its non-stellar appearance in 1677. Scottish astronomer James Dunlop first described it as a globular cluster in 1