MARK GARLICK / SCIENCE PHOTO LIBRARY MARK GARLICK / SCIENCE PHOTO LIBRARY
Birth of galaxies, artwork. Illustration depicting the two possible ways in which galaxies are thought to form. On the left is the bottom-up scenario, in which galaxies are built from smaller building blocks. Small gas clouds collide under gravity to create a large, galaxy-sized structure. Individual cloudlets within this structure then condense into stars, forming a galaxy of stars. On the right is an alternative scenario, the top-down model. Here, galaxies are born from initially much larger cloud structures. These gradually fragment, with the individual fragments then forming into galaxy-sized objects.
Model release not required. Property release not required.