A → planetary nebula
in the constellation → Ursa Major,
one of the four planetary nebulae in → Messier catalog.
It is one of the more complex planetary nebulae known.
Its appearance has been interpreted as that of a cylindrical torus shell
viewed obliquely, so that the projected matter-poor ends of the cylinder
correspond with the Owl’s eyes. Also known as M97 or NGC 3587.
See also: Discovered by Pierre Méchain in 1781, the name goes back to Lord Rosse, who
first used it in 1848. → owl;
→ nebula.