M75
NGC 6864
Dati oggetto
- Designazione catalogo
- M75
- Tipo
- GlobularCluster
- Costellazione
- Sagittarius
- Magnitudine
- 8.5
- Ascensione retta
- 20h 06m 04.8s
- Declinazione
- -21° 55' 16.2"
- Distanza
- 67,500 anni luce
- Dimensione angolare
- 6.0
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Su M75
Descrizione
M75 is a compact, luminous globular cluster in Sagittarius, about 67,500 light-years from Earth — one of the most distant and most concentrated Messier globulars. It has a concentration class I, meaning it has an extremely dense core. The cluster spans about 130 light-years.
Consigli per l'osservazione
Located about 8 degrees south-southwest of Theta Capricorni, in a rather isolated area between Sagittarius and Capricornus. In binoculars it appears as a faint, star-like fuzzy point. A 6-inch telescope shows a small, very concentrated glow. Resolving individual stars is extremely difficult even in large amateur telescopes due to its distance and tight concentration. Best observed from August through October.
Storia
Discovered by Pierre Mechain on August 27, 1780. Charles Messier observed it on October 5, 1780, describing it as a 'nebula without stars.' Due to its great distance and compact nature, it remained unresolved for a long time.
Curiosità
M75 is one of the most luminous Messier globulars in absolute terms. If it were at the same distance as M13 (22,200 light-years), it would be one of the most spectacular globulars in the sky. Its extreme concentration (class I) means its core density is among the highest of any Milky Way globular cluster.
Foto della comunità (1)
Credit: ESA/Hubble & NASA, F. Ferraro et al.. License: CC BY 4.0. (Wikimedia Commons)
Skybred Feb 28, 2026