Galaxy in Leo
M66
The big one of the Leo Triplet, and the one that took the damage — arms pulled out of true, core off-centre, both from a close pass by NGC 3628. The wreckage is a few hundred million years old and has not finished settling.
The asymmetry is visible in a modest telescope as a lopsidedness in the glow, which is unusual — most tidal damage in galaxies is a photographic matter. It also has an unusually high supernova rate for its size, four in the last fifty years, which is what a disturbed galaxy does with the gas the disturbance compressed.
- Catalogue
- M66
- Type
- Galaxy
- Constellation
- Leo
- Distance
- 36 million light-years
- Apparent magnitude
- 8.9
- Surface brightness
- 20.8 mag/□″
- Apparent size
- 8′ × 2.5′
- Right ascension
- 11h 20m
- Declination
- +12.98°
- Found by
- Charles Messier, 1780
Small enough that its 8.9 magnitudes arrive concentrated rather than smeared: 20.8 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 6.
| 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 | Easy | Easy | Easy | Easy |
| Bortle 7 18.6 mag/□″ | No | No | Challenge | Challenge | Challenge |
| Bortle 8 18.1 mag/□″ | No | No | Challenge | Challenge | Challenge |
| Bortle 9 17.8 mag/□″ | No | No | No | No | No |
At the eyepiece
Broader and more irregular than M65 next door, with a visibly uneven brightness across it that is the damage showing. NGC 3628 completes the trio to the north and is the faintest of the three — an edge-on streak that needs a darker sky than the other two.
When, and from where
Highest in the middle of the night in March. Passes overhead at 13°N and rises from everywhere except the far south — below 77°S it never clears the horizon.
| Latitude | Highest it gets | |
|---|---|---|
| 60°N Oslo, Anchorage | 43° | |
| 51°N London, Calgary | 52° | |
| 40°N New York, Madrid | 63° | |
| 30°N Cairo, Houston | 73° | |
| 0°N the equator | 77° | |
| 33°S Sydney, Cape Town | 44° |
Nearby in the sky
The whole catalogue →One more of the catalogue sits within five degrees, close enough to take in on the same night without moving far. Everything below is measured from M66 itself, not from the middle of Leo.
- M65 Galaxy 20′ apart Leo · magnitude 9.3 · binoculars from Bortle 5 or darker
- M105 Galaxy 7.9° apart Leo · magnitude 9.3 · binoculars from Bortle 5 or darker
- M96 Galaxy 8.2° apart Leo · magnitude 9.2 · binoculars from Bortle 5 or darker
- M95 Galaxy 8.9° apart Leo · magnitude 9.7 · binoculars from Bortle 4 or darker
One of 110. Positions J2000; the sky is the final authority.