hmm, just noticed something, not sure if anyone posted this in other threads as i dont have time to go through all of them but...
when you switch to the "lunar orbiter mosaic" imagery taken back in 1960's, the thing disappears, it's only visible in the "visible imagery"
which, if i understand it correctly, was taken in 90's...
1960's picture
1990's picture
not sure if this is caused by lower resolution or because it was put there only recently... whatever it is.