Caption:
NGC 3372, The Eta Carinae Nebula. Eta Carinae is the centerpiece and ionizing star of the great HII region, the Eta Carinae Nebula. The nebula itself spans some 260 light years across, about 7 times the size of the Orion Nebula. Massive is an understatement as the great star weighs in at some 100 to 150 solar masses and shines with the light output of 5 million suns. As one of the most massive stars known, Eta Carinae pushes the theoretical limits on energy output of stars and has attracted much interest among astronomers trying to understand the physics of supermassive stars.