M 108 Deep sky · Galaxy in Ursa Major · M 108 · NGC 3556
Surfboard Galaxy
The Surfboard Galaxy: a spiral seen almost edge-on in the Big Dipper’s bowl, a short hop from the Owl Nebula.
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- Type
- Galaxy
- Designations
- M 108 · NGC 3556
- Constellation
- Ursa Major
- Apparent magnitude
- 10.1
- Apparent size
- 9′ × 2′
- Position (J2000)
- RA 11h 12m · Dec +55° 40′
The full Moon, about 31′ across, is 3.6 times as wide. The Sun comes no nearer to it than 45°, around mid August, so it is never lost in the Sun’s glare, which reaches about 15° out.
When to see it
On the night of Sun 7 Mar 2027, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT | Never sets | 00:11 · 86° | — |
| New York EST | Never sets | 00:06 · 75° | — |
| Singapore GMT+8 | 19:10 | 01:17 · 36° | 07:23 |
| Sydney GMT+11 | 00:19 | 01:07 · 1° | 01:56 |
Common questions
- Can I see it from 50° north?
- Yes, on any clear night of the year. From there it never sets: it is circumpolar, circling the pole and still 16° up at its lowest.
- Can I see it from 35° south?
- No. From there it never rises: you would have to travel north of 34° south before it cleared the horizon at all.
- When is the best time of year to see it?
- Around early March, when it stands opposite the Sun and is highest at midnight. It comes round about two hours earlier each month, so by early June it is highest in the early evening, and in early December not until the hours before dawn.
- How bright is it?
- Magnitude 10.1 in total, but that light is spread over 9′ × 2′ of sky: on average 21.9 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 10.1 it is past the eye, but a 50 mm pair under a dark sky reaches about magnitude 11.0.
Look for
It lies just south-east of Merak, and a low-power eyepiece can hold it and the Owl Nebula at once: a long, mottled streak beside a pale disc.
History
Méchain found it in 1781, but it never made Messier’s printed list. Owen Gingerich added it in 1953, with M 109, from Messier’s own notes.
Look for
From 50° north and 35° north it is circumpolar and never sets; from the equator it climbs to 34°; from 35° south it never rises.
Look for
Magnitude 10.1 against the faintest star each can show: the eye under a city sky, 4.5 (5.6 short); the eye under a dark country sky, 7.0 (3.1 short); 50 mm binoculars under that dark sky, 11.0 (1.0 to spare); a 100 mm telescope there, 12.5 (2.5 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 2% of the field’s width; through a 100 mm telescope at 50×, a field about 1° across, it spans 14% of the field’s width.