M 12 Deep sky · Globular cluster in Ophiuchus · M 12 · NGC 6218
Gumball Globular Cluster
The looser twin of M 10 in Ophiuchus: a globular cluster so open that its stars seem scattered, like gumballs in a jar.
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- Type
- Globular cluster
- Designations
- M 12 · NGC 6218
- Constellation
- Ophiuchus
- Apparent magnitude
- 7.7
- Apparent size
- 16′
- Position (J2000)
- RA 16h 47m · Dec −01° 57′
The full Moon, about 31′ across, is 1.9 times as wide. The Sun comes no nearer to it than 20°, around early December, so it is never lost in the Sun’s glare, which reaches about 15° out.
When to see it
On the night of Mon 31 May 2027, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT+1 | 19:23 | 01:12 · 36° | 07:01 |
| New York EDT | 19:14 | 01:06 · 47° | 06:59 |
| Singapore GMT+8 | 19:18 | 01:17 · 87° | 07:16 |
| Sydney GMT+10 | 18:04 | 00:08 · 58° | 06:12 |
Common questions
- Can I see it from 50° north?
- Yes. It rises and sets, and at its highest it stands 38° up in the south.
- Can I see it from 35° south?
- Yes. It rises and sets, and at its highest it stands 57° up in the north.
- When is the best time of year to see it?
- Around late May, when it stands opposite the Sun and is highest at midnight. It comes round about two hours earlier each month, so by late August it is highest in the early evening, and in early March not until the hours before dawn.
- How bright is it?
- Magnitude 7.7 in total, but that light is spread over 16′ of sky: on average 22.3 magnitudes per square arcsecond. Against a dark country sky that average stands out; a city’s glow drowns all but its brightest parts.
- Naked eye, binoculars or telescope?
- Binoculars. At magnitude 7.7 it is past the eye, but a 50 mm pair under a dark sky reaches about magnitude 11.0.
Look for
Find M 10 first; this one lies a short hop to its north-west, with a gentler glow and no bright core.
Science
It has lost many of its lighter stars to the Milky Way’s pull, each pass through the galaxy’s disk stripping a few more away.
Look for
From 50° north it climbs to 38°; from 35° north it climbs to 53°; from the equator it climbs to 88°; from 35° south it climbs to 57°.
Look for
Magnitude 7.7 against the faintest star each can show: the eye under a city sky, 4.5 (3.2 short); the eye under a dark country sky, 7.0 (0.7 short); 50 mm binoculars under that dark sky, 11.0 (3.3 to spare); a 100 mm telescope there, 12.5 (4.9 to spare). Those limits are for a point of light; its light is spread over its whole size, so it needs some of that margin in hand. Through 7×50 binoculars, whose field is about 7.1° across, it spans 4% of the field’s width; through a 100 mm telescope at 50×, a field about 1° across, it spans 27% of the field’s width.