. A Hubble Space Telescope image shows the Ultraluminous Infrared Galaxy Arp 220, about 250 million light-years away in the constellation Serpens. The image shows the dust-obscured starlight from hundreds of star clusters in a small region of the galaxy about 5,000 light-years across. At the center of the image are two bright knots, where researchers detected magnetic fields. NASA, ESA, and C. Wilson (McMaster University, Hamilton, Ontario, Canada)