Each of the colorful objects in this space wallpaper illustrates one of 30 merging galaxies. The contours in the individual galaxies show the signal strength from carbon monoxide while the color represents the motion of gas. Gas that is moving away from us appears red while the blue color shows gas that is approaching. The contours together with the transition from red to blue indicate a gaseous disc that is rotating about the center of the galaxy.
(Image: © ALMA (ESO/NAOJ/NRAO)/SMA/CARMA/IRAM/J. Ueda et al.)