The Cartwheel galaxy as seen by 3 space telescopes. 100 million years ago, another, smaller galaxy tumbled through the Cartwheel galaxy and left behind "ripples" of star creation. The outer ring is the first ripple, with high ultraviolet output, and the inner yellow spot is from the second ripple, which was smaller and high in infrared output. From NASAimages.org #space #cartwheel | http://exploringuniversecollections.blogspot.com
Supermassive Black Holes: Astronomers have discovered the largest known structure in the universe, a clump of active galactic cores that stretch 4 billion light-years from end to end. The structure is a light quasar group (LQG), a collection of extremely luminous Galactic Nulcei powered by supermassive central black holes!