M55 (Globular Cluster)
A large but somewhat loose globular cluster in Sagittarius. Appears as a big, faintish fuzzy patch in binoculars, easily resolved into stars with a small telescope.
Globular cluster in Sagittarius. Magnitude 6.3.
Can you see it from Guyana?
From Georgetown (6.8° N) it climbs to 52° above the southern horizon at its highest; from Lethem (3.4° N), to 56° above the southern horizon. It is highest at midnight on the night of 15 Jul, in the middle of its season. The page works out tonight's rise, highest point and set for both towns in Guyana time (UTC-4), and where the Moon is.
What you'll see
- Your eyes: Not visible to the eye.
- 10x50 binoculars: A round glow, brighter towards the middle.
- A small telescope (80 to 100 mm): A bright ball; at 100x its edge turns grainy and starts to resolve under dark skies.
- A camera: Spans about 40% of an APS-C frame at 1,500 mm (field 0.9° × 0.6°); needs a tracking mount.
How big, how bright, how far
- Size on the sky: 19′, 61% of the Moon's width (the Moon is about 31′ wide).
- Brightness: magnitude 6.3. Fainter than the faintest stars in Georgetown (4.3) and Lethem (6.0): binoculars or a telescope.
- Distance: 17,400 light-years. The light reaching your eye left it about 17,000 years ago.
What it is made of
- Type
- Globular cluster
- Distance
- Approx. 17,400 Lightyears
- True size
- Approx. 96 Lightyears across (visible extent)
- Mass
- about 200,000 times the Sun's mass
- Notable
- Unusually loose for a globular: concentration 0.76 in the Harris catalogue, looser than all but 14 of 141.
More deep-sky objects: Globular Cluster M22 · M25 (Open Cluster IC 4725) · Ptolemy Cluster (M7) · Eagle Nebula (M16) · Butterfly Cluster (M6) · Wild Duck Cluster (M11)