The Mystery of the Universe's Missing ‘Normal’ Matter Has Begun to Unravel

Previously undetected matter was found in the form of gas filaments between galaxies, which is a major step toward explaining the structure of the cosmos.

This animation shows how the Sunyaev-Zel'dovich Effect (SZE) works across the electromagnetic spectrum. The left panel shows how the same patch of the sky, along the line of sight to a galaxy cluster, appears when observed through various frequency channels, after careful removal of the dominant signals due to the Cosmic Microwave Background (CMB) and to the emission from our Galaxy. The right panel shows a graph displaying the corresponding frequency channel along the electromagnetic spectrum. | ESA/Planck Collaboration