Picture of the largest of Saturn's Titan, made by NASA's Cassini spacecraft in the dark, showed a mysterious glow of Titan's atmosphere.
If you were standing on the surface of Titan, you would not notice this glow, as his power is only a few millionths of a watt. The scientists were able to fix this weak light with a camera apparatus Cassini, allowing you to take pictures with a long exposure.
The researchers were surprised to find that the picture glow emanates not only from the top of Titan's atmosphere - where it would be expected - but also from the deeper layers below the atmospheric "haze" of Titan, which is a couple of volatile organic compounds.
Scientists believe that the emission of visible light from the deep layers of Titan's atmosphere may be caused by deeply penetrating cosmic rays or the chemical reaction involving glow.
The study was published in the journal Geophysical Research Letters.