Now how did they figure that out? It's rather astonishing that astronomers can detect exoplanets at all, but detecting a cosmic collision of two relatively small objects and the dust they left behind -- wow.
A bit off topic, but the author wrote "the dust cloud is made up of minute particles a 50th of the diameter of a human hair." I am shocked, shocked he didn't say "50 times smaller than a human hair" as most writers are wont to do these days.
Yeah, writing it the right way probably means the reporter was given a small box to clean out the desk and get out.