M66
NGC 3627
Properties
Position & Identifiers
Visibility
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Eyepiece View
M66 · 10.3′×4.6′ · N up, E left
Surface Brightness & Visibility
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About M66
Description
M66 is the largest and brightest member of the Leo Triplet, about 36 million light-years from Earth. It is a spiral galaxy spanning about 95,000 light-years with noticeably asymmetric spiral arms — distorted by gravitational interactions with its neighbors M65 and NGC 3628. The galaxy has hosted four observed supernovae.
Observing Tips
Located just 20 arcminutes east of M65 — the two galaxies share the same low-power field. M66 is slightly brighter and larger than M65. A 4-inch telescope shows an elongated glow. An 8-inch reveals an asymmetric brightness distribution and hints of spiral structure. The three galaxies of the Leo Triplet can be seen together in a wide-field eyepiece. Best observed from March through June.
History
Discovered by Charles Messier on March 1, 1780, together with M65. Four supernovae have been observed in M66: 1973R, 1989B, 1997bs, and 2009hd — making it one of the more prolific supernova hosts.
Fun Facts
M66's spiral arms are clearly asymmetric and displaced from center — pulled out of shape by the gravitational tug-of-war with M65 and NGC 3628. Its high star formation rate and four observed supernovae may be linked to this gravitational interaction, which compresses gas and triggers star formation.