The scientists were looking in the infrared and saw the "scar" from the impact. Leigh Fletcher, a NASA postdoctoral fellow at JPL who helped in getting these latest observations said, "Given the rarity of these events, it's extremely exciting to be involved in these observations. These are the most exciting observations I've seen in my five years of observing the outer planets!"
This really is a extremely exciting discovery. This is also a great example of how amateurs can make real contributions to science. A few weeks ago, a fourteen-year-old discovered a new type of supernova. There are groups of amateurs that study variable stars. Astronomy really is a special field because the wonders of space are there for anyone with a telescope. If you don't have a telescope, find a local astronomy club. Most amateur astronomers want nothing more than to share the wonder of seeing these things with your own eyes. I don't know how long this impact scar will be visible so get out there and see it while you have a chance. Astronomy is by no means the only field that amateurs can make big contributions to. There is no better way to get a appreciation and understanding for the sheer beauty of science, then going out and doing it yourself.
For more information-
Universe Today
NASA
Keck
Image Credit- Credit: Paul Kalas (UCB), Michael Fitzgerald (LLNL/UCB), Franck Marchis (SETI Institute/UCB), James Graham (UCB)