It's often hard to wrap our minds around what will excite the people of the world. If you take a look at the originator of a viral Twitter post or video, it's not uncommon for them to be just as baffled at their work's success as anyone else.
But although we don't know what elevates certain images to prominence over others besides luck and attention, it's sometimes easy to see what about these images was worth talking about.
Sometimes they tie into a specific social issue, or sometimes they just present such a striking scene that we can't ignore them. But however they got there, these photos made quite the impression this week.