Observing and reporting impacts
Keep an eye out for asteroid strikes on Jupiter
The gravitational pull of the gas giants inevitably leads to asteroid impacts. Those large enough to leave a mark are infrequent, but several have been reported and imaged on Jupiter in recent years (none have been reported on Saturn to date.)
As amateurs observe and image the planets regularly, they are the ones most likely to see and report such events. If it’s a big impact that leaves a ‘scar’, professional observatories may divert busy schedules to take a look too. So it's important to report an impact site’s location accurately.
It takes experience to make a visual-only impact claim, but if the impact has been imaged, it’s easy to locate using WinJupos’s measurement scheme (available for free at http://jupos.org).
A non-scar impact typically appears as a brief flash. Impacts may occur when you’re looking away, so postcapture analysis with specialist software, such as DeTeCt, can help. If you want to follow this route further, look at the Planetary Virtual Observatory and Laboratory (PVOL) at http://pvol2.ehu.eus/psws/jovian_impacts.