The Eta Carina Nebula is one of the most spectacular objects in the sky, and the
brightest of all the emission nebulae. It appears as an oval patch in the Milky Way
within the southern constellation Carina, brighter and 4 times larger than the
Orion Nebula. It is 260 light years across, and 8000 light years from earth. This image
shows only the central portion of the much larger nebula.

The main source of power lighting up the nebula is the star Eta Carina. This star
seemed to be an unremarkable 4th magnitude star when first catalogued in the 17th
century. But it soon began brightening, and after a massive outburst in 1843,
it brightened dramatically until it was the 2nd brightest of all the stars,
second only to Sirius. The star faded, however, and within a couple of decades
it was no longer visible to the naked eye. It has slowly brightened again, however,
during the opening decades of the 21st century, and is visible once again without
a telescope.

During the dramatic 1843 eruption, Eta Carina emitted as much
light as a typical supernova, though the star was not blown apart. Eta Carina is a rare
star, with 100-150 times the mass of the sun; there are probably only a few dozen stars like
this in the whole galaxy. Eta Carina also puts out 4 million times as much energy as
the sun. In 6 seconds, Eta Carina produces more energy than the sun does in
an entire year. Its massive size and instability make Eta Carina a prime candidate for
a supernova explosion.

Image data:
Telescope: Planewave 17"
Camera: SBIG STXL-11002
Exposure: Red, Green, Blue: 2 hours each
Hydroden-alpha, Oxygen-III, Sulfur-II: 4 hours each
(total exposure = 18 hours)
Location: Heaven's Mirror Observatory, New South Wales, Australia