M4 (NGC 6121)
Also known as M4 · M 4 · NGC 6121
M4 (NGC 6121) is a globular star cluster in the constellation Scorpius, about 6,520 light-years from Earth.
Facts
| Type | Globular star cluster |
|---|---|
| Constellation | Scorpius |
| Position (J2000) | 16h 23m 35s, −26° 31′ |
| Distance | 6,520 light-years (its light set off about 6,520 years ago) |
| Brightness | magnitude 5.4 (smaller is brighter; the faintest stars the eye sees are about 6) |
| Size on the sky | 26.3′ × 26.3′ (the full Moon is about 31′) |
| Filter | No filter (It shines in starlight of every colour, so a nebula filter would only dim it; a dark sky helps more.) |
| Studied in | 2,004 scientific papers (SIMBAD) |
When and how to see it
M4 (NGC 6121) is highest in the sky at midnight in May. From India (about 20° N) it climbs to about 43° above the horizon; from 50° N, to about 13°. To see it you need the naked eye from a dark site.
Heights are worked out for India and for 50° N. Set your location in Settings to see them for where you are.
For tonight's best time from your own town, the darkness and the Moon, open it on the map and see its "Tonight from your location" card.
More in Scorpius
- Butterfly Cluster (M6)
- Butterfly Nebula
- Cat's Paw Nebula
- Fried Egg Nebula
- M80 (NGC 6093)
- Prawn Nebula
- Ptolemy Cluster (M7)
- War and Peace Nebula
Everything in Scorpius · All 88 constellations · All sky objects
Data: SIMBAD (CDS, Strasbourg; the site's weekly copy) · OpenNGC · Data sources & credits