Solar System Passed Through Cold Interstellar Cloud About 2 Million Years Ago, Study Suggests

This image shows the position of NASA’s Voyager 1 and Voyager 2 probes, relative to the heliosphere. Image credit: NASA / JPL-Caltech.

Cold, dense clouds in the interstellar medium of our Milky Way Galaxy are around four-five orders of magnitude denser than their diffuse counterparts.