This illustration shows the size of the debris disc observed around the star Fomalhaut, as compared to the size of the Kuiper Belt and Asteroid Belt in the Solar System. The upper image shows the star Fomalhaut surrounded by its debris disc, which is located at a radius of about 130 astronomical units (AU) from the star. A candidate planet, Fomalhaut b, detected around the star in 2008, is also indicated; this detection is, however, still under debate.
Abell 520 is the site where two massive clusters of galaxies - containing 100s or 1000s of galaxies *each* - are colliding. As cool as that is, what the heck is going on with the dark matter? It's a puzzle astronomers don't have an answer for just yet. Click for more. Image credit: NASA, ESA, CFHT, CXO, M.J. Jee (University of California, Davis), and A. Mahdavi (San Francisco State University)