Editing Stephan's Quintet (section)

===Molecular hydrogen emission===

The [[NASA]] [[Spitzer Space Telescope]], which detects infrared radiation, discovered a very powerful molecular hydrogen signal from the shock wave between the galaxies. This emission is one of the most turbulent formations of molecular hydrogen ever seen, and the strongest emission originates near the center of the green area in the visible light picture discussed earlier. This phenomenon was discovered by an international team led by scientists at the [[California Institute of Technology]] and including scientists from Australia, Germany and China. The detection of molecular hydrogen from the collision was initially unexpected because the hydrogen molecule is very fragile and is easily destroyed in shock waves of the kind expected in Stephan's Quintet. However, one solution is that when a shock front moves through a cloudy medium like the center of the group, millions of smaller shocks are produced in a turbulent layer, and this can allow molecular hydrogen to survive.
[[File:Stephans Quintet sdss-g Goran Nilsson & The Liverpool Telescope.jpg|thumb|Earthbound monochrome (sdss-g filtered) image of Stephan's Quintet from the [[Liverpool Telescope]]]]