The article in the link above shows a memorable moment that happened only a few months ago, it was of course the death of the King Of Pop. People will remember him because of his unique voice and performances. Also he will never stop making money because companies will use his music and release it over and over again. So he will never truly be forgotten.
For the next memorable world, it was the story that shook the world and took up all the attention of the media, gaining worldwide interest. It was the 911 attacks, it drew the worlds attention and made many countries strengthen there laws. Even today when a attack from the east is made they still refer to the 911 attacks keeping the event in the public’s eye.