NGC 3372 - Eta Carinae Nebula

NGC 3372, the Eta Carinae Nebula, also known as the Great Nebula in Carina, is a large bright nebula that surrounds several open clusters. The nebula can be seen with the naked eye. The star Eta Carinae, a giant variable star, is among the most massive and luminous stars in the Milky Way.

The central part of NGC 3372 is known as the Keyhole Nebula, a famous dark zone seen near Eta Carinae. With binoculars one can see the nebula, which appear as three fan shaped areas with dark lanes in between. The Eta Carinae Nebula was discovered by Nicolas Louis de Lacaille in 1751-52 from the Cape of Good Hope.

This first magnitude nebula is one of the largest H II regions in the Milky Way and is one of the largest diffuse nebulae in the sky. Although it is some four times as large and much brighter than the famous Orion Nebula, the Carina Nebula is less well known, due to its location far in the Southern Hemisphere. The nebula lies at an estimated distance between 6,500 and 10,000 light years from Earth.

Within the large bright nebula is a much smaller feature, immediately surrounding Eta Carinae itself. This small nebula is known as the Homunculus Nebula (from the Latin meaning Little Man), and is believed to have been ejected in an enormous outburst in 1841, which briefly made Eta Carinae the second-brightest star in the sky.