The implications that the spot can disappear inside the observer era is interesting. I had assumed it was a multi-epoch spanning structure, not something which

The implications that the spot can disappear inside the observer era is interesting. I had assumed it was a multi-epoch spanning structure, not something which was ephemeral inside human recorded observations. Watching the TV broadcasts of the comet collisions "string of pearls" was amazing. Watching a slow fade on the spot might be something which requires a decades-long movie capture. (obviously, periodic stills being combined over 10-20 years)