Galaxy in Andromeda
M32
A dwarf galaxy orbiting Andromeda, and probably what remains of something much larger after Andromeda took the rest. Its centre is packed to an almost unimaginable degree — something like a hundred million times the density of stars around the Sun.
The stripping is not speculation: streams of stars pulled out of it lie draped across Andromeda's disc, and the shape of the debris implies it was once a spiral several times its present size. At the eyepiece it is a small bright oval that most people mistake for a defocused star on the first pass.
- Catalogue
- M32
- Type
- Galaxy
- Constellation
- Andromeda
- Distance
- 2.5 million light-years
- Apparent magnitude
- 8.1
- Surface brightness
- 20.9 mag/□″
- Apparent size
- 8′ × 6′
- Right ascension
- 0h 43m
- Declination
- +40.87°
- Found by
- Guillaume Le Gentil, 1749
Small enough that its 8.1 magnitudes arrive concentrated rather than smeared: 20.9 per square arcsecond, which is why it stands out from the sky better than its brightness alone suggests. Why surface brightness is the number that matters.
Could you see it?
Straightforward with 10×50 binoculars from Bortle 5.
| Sky | Eye | 10×50 | 80mm | 130mm | 200mm |
|---|---|---|---|---|---|
| Bortle 1 21.9 mag/□″ | No | Easy | Easy | Easy | Easy |
| Bortle 2 21.7 mag/□″ | No | Easy | Easy | Easy | Easy |
| Bortle 3 21.4 mag/□″ | No | Easy | Easy | Easy | Easy |
| Bortle 4 20.9 mag/□″ | No | Easy | Easy | Easy | Easy |
| Bortle 5 20.3 mag/□″ | No | Easy | Easy | Easy | Easy |
| Bortle 6 19.3 mag/□″ | No | Challenge | Challenge | Challenge | Challenge |
| Bortle 7 18.6 mag/□″ | No | Challenge | Challenge | Challenge | Challenge |
| Bortle 8 18.1 mag/□″ | No | No | No | No | No |
| Bortle 9 17.8 mag/□″ | No | No | No | No | No |
At the eyepiece
A small, bright, featureless ball sitting close enough to Andromeda's core that it is easy to mistake for a star at low power. There is nothing to resolve and nothing to wait for. Its interest is entirely in knowing what it is — the surviving centre of something Andromeda dismantled.
When, and from where
Highest in the middle of the night in September. Well placed for the northern hemisphere and overhead for anyone near 41°N. South of 49°S it stays below the horizon.
| Latitude | Highest it gets | |
|---|---|---|
| 60°N Oslo, Anchorage | 71° | Never sets |
| 51°N London, Calgary | 80° | Never sets |
| 40°N New York, Madrid | 89° | |
| 30°N Cairo, Houston | 79° | |
| 0°N the equator | 49° | |
| 33°S Sydney, Cape Town | 16° | Low — in the murk |
Nearby in the sky
The whole catalogue →2 more of the catalogue sit within five degrees, close enough to take in on the same night without moving far. Everything below is measured from M32 itself, not from the middle of Andromeda.
- M31 Andromeda Galaxy 24′ apart Andromeda · magnitude 3.4 · binoculars from Bortle 4 or darker
- M110 Galaxy 55′ apart Andromeda · magnitude 8.5 · binoculars from Bortle 3 or darker
- M33 Triangulum Galaxy 15° apart Triangulum · magnitude 5.7 · binoculars from Bortle 3 or darker
- M76 Little Dumbbell 15° apart Perseus · magnitude 10.1 · binoculars from Bortle 4 or darker
One of 110. Positions J2000; the sky is the final authority.