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NGC 7009 - the Saturn nebula

For this image of the Saturn Nebula, the worst images were sorted out from 1000 images in each of the colour channels. The remaining images are almost 600 frames through the red and green filter, as well as almost 900 frames for the blue channel. The seeing in the stacked images reached values around 2.1''. The almost full Moon was only between 15 and 45 degrees away from NGC 7009 during the exposures.
Object description:

The Saturn Nebula (NGC 7009) is a planetary nebula in the constellation Aquarius and is located in a distance of about 5000 light years from the solar system. It was discovered on 7 September 1782 by Friedrich Wilhelm Herschel. The name was given by Lord Rosse because the shape of the jets reminds him of Saturn's rings.

Planetary nebulae have nothing to do with planets. This term was introduced by Herschel because the similarity of these often unstructured objects with the planet Uranus.

« Click here or the thumbnail image for a comparison with the size of the Moon

The physical formation of planetary nebulae is principally understood today. The Saturn Nebula was originally a star of low mass. Towards the end of its life, it expanded into a red giant star and repelled its outer gas layers. The remaining one, extremely hot (50,000 K), core of the star causes the gas layers to light up in colour due to strong ultraviolet radiation. The star has
developed into a white dwarf star, which is clearly visible in our image. Double ionized oxygen is responsible for the characteristic fluorescent green of the nebula. The diameter of the Saturn Nebula is about 0.5 light years. It lies in a very starless region and seems to "float in nothingness".

Our sun will maybe suffer a similar fate in about 4.5 billion years at the end of its life and will also produce a colourful planetary nebula.

A high-resolution image of the Hubble Space Telescope from the Saturn Nebula can be found here and a detailed object description with many ESO images here.

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