Quasars, actually quasi-stellar objects (QSO), are among the brightest space objects we know of. A quasar accretion disc is formed as the object circles a black hole and is slowly torn apart. According to the lead scientist in imaging one, "a quasar accretion disc has a typical size of a few light-days, or around 100 billion kilometres across, but they lie billions of light-years away. This means their apparent size when viewed from Earth is so small that we will probably never have a telescope powerful enough to see their structure directly." NASA and ESA astronomers used the Hubble Space Telescope in conjunction with gravitational lensing (see the embedded QuickTime object below for an example) to produce a highly detailed image of a quasar and its accretion disc in order to accurately measure it's size, shape and temperature. Using this technique, the team was able to determine (and image) a distant, faint object only 4-11 light days across.