Globular cluster
M 15 (NGC 7078)
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 0.4 % of the Sun’s. Distance, brightness and structure come from the Harris catalogue.
| Type | Globular cluster |
|---|---|
| Constellation | Pegasus |
| Distance | 10,400 pc (33.9 thousand ly) |
| Metallicity [Fe/H] | -2.37 |
| Half-light radius | 3.0 pc |
| Central concentration (c) | 2.29 · core-collapsed |
| Radial velocity | -107.0 km/s |
| Source | Harris 1996 (2010) |
| Right ascension (J2000) | 21h 29m 58.3s |
| Declination (J2000) | +12° 10′ 01″ |
In the sky
Visible from the whole Northern Hemisphere and south to latitude 78° S. North of latitude 78° N it never sets. It stands highest at midnight in August, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out 34 thousand years ago. At that time Homo sapiens was spreading out of Africa; there was no farming yet. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 602 million years.