Dust cloud echo's

Great article in Time at the moment - http://www.time.com/time/health/article/0,8599,2106904,00.html?xid=gonewsedit

This bit blows my mind
It gets even better. The 1843 flare-up played out over 20 years, which means the light-echo version will do the same. "We took observations nine months ago," says Rest, "and we were looking at 1843. Now we're looking at 1844. It's like a movie. It's really cool.

I wonder what else we can see from reflections we arent able to track at the moment, eg like ripples in time from our own planet.