Keyhole Nebula, image Gerry Aarts
The dark Keyhole Nebula, visible in the picture above by the president of the Western Sydney Amateur Astronomical Group, Gerry Aarts,is part of the Eta Carinae Nebula. If you are at a dark spot in the country away from lights, you can see this nebula with your naked eye as a bright knot in the Milky Way, not far from the Southern Cross.
Also visible in Gerry’s picture is a bright star to the right of centre. That it the star Eta Carinae itself. Situated about 8000 light years from our Sun, it is a massive star that is at least 100 times more massive than the Sun.
Eta Carinae surrounded by dust lobes, imaged by the Hubble Space Telescope. Courtesy Credit: Jon Morse (University of Colorado), and NASA
In the 1840s Eta Carinae brightened and became the second brightest star in the sky. During that period it ejected two dust lobes that are slowly expanding away from the star. These can be easily seen in the famous Hubble Space Telescope image above.
Astronomers think that Eta Carinae is highly unstable and may become explode as a supernova at any time. Of course, as light from the star takes 8000 years to reach us, that may have already happened!