Omega Centauri

cluster

Omega Centauri (NGC 5139) — the largest and brightest globular cluster of the Milky Way, some 10 million stars packed into a ball ~150 light-years across, ~17,000 light-years away. It may be the stripped core of a dwarf galaxy the Milky Way swallowed.

Open in 3D viewSee Omega Centauri in the live, interactive 3D map

Science

Classification

Type: Globular star cluster (possibly a stripped dwarf-galaxy core)
Distance: ~17,000 light-years
Diameter: ~150 light-years
Stars: ~10 million · estimated
Age: ~11.5 billion years

How we know

Note: A real Hubble image at the cluster's real galactocentric position. It is only ~150 light-years across — shown enlarged as a marker so it's visible at galaxy scale, as seen from Earth.

Discovery & history

Name: Named as if a star ('Omega Centauri') in Bayer's 1603 atlas, before its true nature was known.

Catalogued as a 'star' by Ptolemy (~150 AD); Edmond Halley recognised it as a non-stellar object in 1677; John Herschel resolved it into stars in the 1830s.

Images

Omega Centauri — the Milky Way's largest globular cluster (Hubble) — NASA, ESA / Hubble (public domain) · Wikimedia Commons

Images from open archives · credit shown per image