What do you think had the most impact on planet earth in the last 100 years and why? It can be anything, you can choose an assination of a president, 9/11, World War 1 and 2. It can be an invention. Anything that you can think of. Something that you believe had the most impact on planet Earth in the last 100 years. Now I was going to put this in the mature discussion section, but I believe you people can be serious and discuss this maturely, I dont want this topic to be turned into fun and games. I want it to be serious. Discuss.