A boulder changes address on a comet
Compare Rosetta’s real before-and-after photographs, then follow the archive investigation that narrowed the missing journey to a much shorter interval.
What to keep in mind
The panels have different scales and dates and do not record continuous movement. The later reanalysis revises the early timing interpretation; the trigger remains unsettled.
Find the same terrain twice
Use surrounding features and the preserved scale bars to locate the marked boulder in both panels. Which apparent changes could simply follow from image scale?
Read what the dates establish
These views bracket a long interval. What would a closer before-and-after pair add, and why can neither pair alone reveal the boulder’s exact route?
What would distinguish the triggers?
Compare outburst propulsion, destabilisation and local outgassing as explanations. Which visible terrain detail matters, and which missing observation would separate the mechanisms?