J002E3
> One explanation could have been that it was a 30-meter-wide piece of rock, but University of Arizona astronomers found that the object's electromagnetic spectrum was consistent with white titanium dioxide paint, the same paint used by NASA for the Saturn V rockets.<p>I know this is a really old thing but the idea that we can determine composition of the surface of an object from so far away simply by looking at the light it reflects is absolutely incredible to me. Very science fiction. :)