Astronomy Picture of the Day

Explanation: The dark dusty Keyhole Nebula gets its name from its unusual shape. Designated NGC 3324, the Keyhole Nebula is a smaller region superposed on the bright Eta Carina Nebula. The Eta Carina Nebula is the largest nebula in angular extent on the sky, larger than the famous Orion Nebula, but its southerly location makes it less familiar to Northern Hemisphere skywatchers. The star Eta Carinae itself is extremely variable and has faded in a mere 150 years - formerly one of the brightest in the sky it is now invisible without a telescope. The nebula created by the star's 19th century outburst has been photographed by the Hubble Space Telescope.