M66, together with its neighbours M65 and NGC 3628, forms a conspicuous and picturesque trio of large spiral galaxies, known as the Leo Triplet or M66 group, located at a distance of about 35 million light years. In the lower image, M66 is on the lower left, M65 is lower right and NGC 3628 is upper left.

Astronomers suspect that the galaxy's distorted shape is due to its ongoing gravitational interactions with its neighbours M65 and NGC 3628. M66 is a brilliant example of a barred spiral galaxy, the most common type of disk galaxy in the local Universe. Its blue core and bar-like structure illustrates a concentration of older stars. While the bar seems devoid of star formation, the ends are bright red and actively forming stars. A barred spiral offers an exquisite laboratory for star formation because it contains many different environments with varying levels of star-formation activity, e.g., nucleus, rings, bar, the bar ends and spiral arms.

M66 is considerably larger than its neighbour, M65, and has a well developed but not well defined central bulge. Its spiral arms are deformed, probably because of encounters with its neighbours. They seem to be distorted and displaced above the plane of the galaxy. Note how one of the spiral arms seems to pass over the side of the central bulge. Much dust is visible here, as well as a few pink nebulae, signs of star formation, near the end of one of the arms.

M67 is not the oldest known open cluster in the galaxy, but there are very few known to be older. It is an important laboratory for studying stellar evolution since, apart from 30 anomalous blue stragglers, all its stars are at the same distance and age.

The age of this open cluster is estimated at between 3.2 and 5 billion years. If, as most recently estimated, the age is closer to four billion years the stars of M67 are likely to be slightly younger than our Sun.

M67 has more than 100 stars similar to the Sun plus many red giants. The total star count is estimated at over 500. The cluster contains no main sequence stars bluer than spectral type F, other than perhaps some of the blue stragglers, since the brighter stars of that age have already left the main sequence. In fact, when the stars of the cluster are plotted on the Hertzsprung-Russell diagram, there is a distinct "turn-off" representing the stars which are just about to leave the main sequence and become red giants. As the cluster ages, the turn-off will move down the main sequence.

Due to its southern declination, M68 can be fairly difficult to observe from northern latitudes.

Showing as just a faint patch in binoculars, the brightest stars of M68 begin to be resolved by telescopes starting from 4-inch aperture under good conditions, appearing as a mottled round nebulous patch with a bright center gradually fading towards its edges. A 6-inch telescope resolves the outer parts of the cluster and larger telescopes show a rich cluster to the core.

M69 is at a distance of about 29,700 light years from Earth with a spatial radius of 42 light years. It is a close neighbour of another globular cluster M70 with 1,800 light years separating the two. Both clusters lie close to the Galactic Center.

M69 and M70 are a couple of the smallest and fainter of Messier´s globular clusters. In good conditions, on a dark night, they should be seen through 7x50 or 10x50 binoculars and better resolved through telescopes.

M69 is one of the most metal rich globular clusters known.

Appearing roughly the same brightness and size as its neighbour M69, M70 is in fact a little more luminous and little bigger. Both globular clusters are quite close to the galactic center and hence subject to tidal gravitational forces.

Globular cluster M70 became famous in 1995 when the comet Hale-Bopp was discovered near it by Alan Hale and Thomas Bopp as they were observing M70.