Globular cluster
M 4 (NGC 6121)
Globular cluster
A globular cluster of hundreds of thousands of old stars orbiting in the Galaxy’s halo: among the oldest objects of the Milky Way, about 12 billion years old. Its metal abundance is 6.9 % of the Sun’s. Distance, brightness and structure come from the Harris catalogue.
| Type | Globular cluster |
|---|---|
| Constellation | Scorpius |
| Distance | 2,200 pc (7.2 thousand ly) |
| Metallicity [Fe/H] | -1.16 |
| Half-light radius | 2.8 pc |
| Central concentration (c) | 1.65 |
| Radial velocity | 70.7 km/s |
| Source | Harris 1996 (2010) |
| Right ascension (J2000) | 16h 23m 35.2s |
| Declination (J2000) | −26° 31′ 33″ |
In the sky
Visible from the whole Southern Hemisphere and north to latitude 63° N. South of latitude 63° S it never sets. It stands highest at midnight in May, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out 7,176 years ago. At that time the first farming villages were being founded; there was no writing yet. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 127 million years.