Planetary nebula in Ursa Major
Owl Nebula (M97)
The Owl, for two darker patches in the disc that read as eyes — an impression that survives at the eyepiece in a 200mm telescope and is one of the more satisfying moments in the catalogue. Lord Rosse named it from his drawing in 1848.
The eyes are not holes but a barrel of gas seen through its own long axis, where there is less material in the line of sight. It is around eight thousand years old and among the more evolved planetaries here, which is why it is faint: the gas has expanded far enough to be thinning out.
- Catalogue
- M97
- Type
- Planetary nebula
- Constellation
- Ursa Major
- Distance
- 2,030 light-years
- Apparent magnitude
- 9.9
- Surface brightness
- 20.9 mag/□″
- Apparent size
- 3′
- Right ascension
- 11h 15m
- Declination
- +55.02°
- Found by
- Pierre Méchain, 1781
Small enough that its 9.9 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 4.
| 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 | No | Challenge | Challenge | Challenge |
| Bortle 6 19.3 mag/□″ | No | No | No | No | No |
| Bortle 7 18.6 mag/□″ | No | No | No | No | No |
| Bortle 8 18.1 mag/□″ | No | No | No | No | No |
| Bortle 9 17.8 mag/□″ | No | No | No | No | No |
At the eyepiece
The two dark patches really do read as eyes, and seeing them is one of the small pleasures of this catalogue — 200mm and an OIII filter is roughly where they arrive. Without a filter it is a soft round grey disc and the eyes stay hidden.
When, and from where
Highest in the middle of the night in March. Well placed for the northern hemisphere and overhead for anyone near 55°N. South of 35°S it stays below the horizon.
| Latitude | Highest it gets | |
|---|---|---|
| 60°N Oslo, Anchorage | 85° | Never sets |
| 51°N London, Calgary | 86° | Never sets |
| 40°N New York, Madrid | 75° | Never sets |
| 30°N Cairo, Houston | 65° | |
| 0°N the equator | 35° | |
| 33°S Sydney, Cape Town | 2° | Low — in the murk |
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 M97 itself, not from the middle of Ursa Major.
- M108 Galaxy 48′ apart Ursa Major · magnitude 10.0 · binoculars from Bortle 4 or darker
- M109 Galaxy 6.5° apart Ursa Major · magnitude 9.8 · binoculars from Bortle 4 or darker
- M40 Winnecke 4 9.8° apart Ursa Major · magnitude 8.4 · binoculars from Bortle 7 or darker
- M106 Galaxy 13° apart Canes Venatici · magnitude 8.4 · binoculars from Bortle 4 or darker
One of 110. Positions J2000; the sky is the final authority.