Milky Way
Globular
Clusters
Index
1. Introduction
2. Orbits
3. Omega Centauri
4. 47 Tucanae
5. 47 Tuc Core
6. 47 Tuc Blue Stragglers
7. M4
8. M5
9. M10
10. M13
11. M15
12. M22
13. NGC 6522
14. Galactic Centre Chart
15. List of MW Globulars
16. Credits and Links
M13
M13, also known as the Hercules Globular Cluster and NGC 6205 is in constellation Hercules. With an apparent magnitude of 5.8, it is just visible with the naked eye from a clear, dark site. It is easily seen in binoculars and small telescopes. Its angular diameter is about 23 arc minutes. M13 is 25,100 light-years distant. Its actual diameter is about 145 light-years. It contains several hundred thousand stars, Its brightest star, the variable star V11, is apparent magnitude 11.95.
In 1974, a message was sent towards this globular cluser from the Arecibo Radio Telescope. The senders reasoned that its higher star density increased the chance of their message reaching a planet with intelligent life forms.