M72 (Globular Cluster)
A faint, distant globular cluster in Aquarius, about 54,000 light-years away. Unusually, most of its red giants are first-generation stars.
Globular cluster in Aquarius. Magnitude 9.3.
Can you see it from Guyana?
From Georgetown (6.8° N) it climbs to 71° above the southern horizon at its highest; from Lethem (3.4° N), to 74° above the southern horizon. It is highest at midnight on the night of 2 Aug, in the middle of its season. The page works out tonight's rise, highest point and set for both towns in Guyana time (UTC-4), and where the Moon is.
What you'll see
- Your eyes: Not visible to the eye. It lies 11.7° south-west of Sadalsuud.
- 10x50 binoculars: Just detectable in binoculars from a dark site, as a faint smudge.
- A small telescope (80 to 100 mm): A small, faint glow; it needs a dark sky and high power to look granular. M73 is 1.3° to the east.
- A camera: Tiny on camera: it needs 2,000 mm or more of focal length on a tracking mount.
How big, how bright, how far
- Size on the sky: 4.5′, 14% of the Moon's width (the Moon is about 31′ wide).
- Brightness: magnitude 9.3. Fainter than the faintest stars in Georgetown (4.3) and Lethem (6.0): binoculars or a telescope.
- Distance: 54,300 light-years. The light reaching your eye left it about 54,300 years ago.
- True size: 71 light-years across its catalogued outline; light crosses it in 71 years.
Apparent size from OpenNGC (Mattia Verga), CC-BY-SA-4.0.
What it is made of
- Type
- Globular cluster
- Mass
- About 80,000 times the Sun's mass
- Notable
- Its photograph was the first image ever published in the ESA/Hubble Picture of the Week series, in April 2010.
Measured: Which generation its red giants belong to (389 measured near its centre).
- First generation: 54.2%, ± 2.7%
- Second generation: 45.8%, born from gas the first stars enriched
Gas: searches of globular clusters mostly find only upper limits (Pancino et al. 2024, arXiv:2404.05548). Hubble ultraviolet colours split its red giants into a first generation and later, chemically enriched ones: 54.2% ± 2.7% first generation among 389 red giants (NGC 6981; Milone et al. 2017, MNRAS 464, 3636, Table 2).
Also in it, not measured:
- Stellar remnants: white dwarfs and neutron stars
- Almost no gas or dust: not in this tally
How we know: Distance from Gaia, Hubble and earlier distances to its stars, combined: Baumgardt & Vasiliev 2021, MNRAS 505, 5957; Baumgardt globular cluster database, combined_table.txt, retrieved 2026-10-21 (NGC 6981: 16.66 +/- 0.18 kpc). True size: the apparent size times the distance (apparent size: OpenNGC (Mattia Verga, CC BY-SA 4.0), commit 4e2398a2). Mass: Baumgardt globular cluster database, combined_table.txt (NGC 6981: 81,200 ± 12,800 Suns), retrieved 2026-10-21; Baumgardt & Vasiliev 2021, MNRAS 505, 5957.
More deep-sky objects: M75 (Globular Cluster) · M2 (Globular Cluster) · M30 (Globular Cluster) · M55 (Globular Cluster) · Globular Cluster M15 · Wild Duck Cluster (M11)