Messier 47 — Open Cluster in Puppis

M47 is a bright, coarse open star cluster in the constellation Puppis, located about 1,600 light-years from Earth. It contains roughly 50 stars spanning about 12 light-years, with an apparent diameter of about 30 arcminutes — comparable to the full Moon. At magnitude 4.4, it is visible to the naked eye as a hazy patch under dark skies. The cluster is approximately 78 million years old — relatively young. Its brightest stars are hot blue-white B-type stars of about magnitude 5.7, and the cluster includes several attractive double stars, including Sigma 1121 near the center.

Located about 5 degrees west of M46 and roughly 12 degrees east of Sirius. Visible to the naked eye from dark sites. Binoculars give a beautiful view, showing about 20 bright stars loosely scattered across a degree-wide field. A telescope at 25-50x is ideal, revealing the bright blue-white stars and several double stars, including the attractive close pair near the center. M47 and M46 can be framed together in a wide-field binocular view, offering a magnificent contrast. Best observed from January through March when Puppis is at its highest.

Discovered by Giovanni Battista Hodierna before 1654. Charles Messier independently cataloged it in 1771, but made an error in recording its position — he listed coordinates that pointed to an empty patch of sky. This error caused M47 to be considered a 'missing Messier object' for over a century until T.F. Morris identified it in 1959 by matching Messier's description to NGC 2422.