The Helix Nebula
Blue is oxygen. Red is hydrogen and nitrogen. The colours are the chemistry, not an effect.
NGC 7293 lies about 650 light-years away in the constellation Aquarius, which makes it one of the nearest planetary nebulae to Earth. This picture is a composite. Nine ultra-sharp frames from the Advanced Camera for Surveys aboard the Hubble Space Telescope were blended with a wide-field exposure from the Mosaic Camera on the WIYN 0.9-metre telescope at Kitt Peak National Observatory.
Look into the blue and the ring is not smooth. Comet-shaped knots stand out against it, each trailing a tail that points away from the centre, and a web of filaments the astronomers call bicycle spokes runs through the gas. NOAO and the Space Telescope Science Institute released the picture on 9 May 2003, for Astronomy Day.
NASA, NOAO, ESA, the Hubble Helix Nebula Team, M. Meixner (STScI), and T.A. Rector (University of Alaska Anchorage/NSF NOIRLab). Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0). Source record.