Thread:Comments:Meteorites in Morocco found to be from Mars/Some information missing

1. How can anyone know with certainty that any of the meteorites really are Martian in origin? 2. It says there have been 24,000 meteorites - When? What time frame are we talking about? Who is counting, and how could anyone know how many meteorites have hit the Earth in any time frame? Is this just an estimate, and if so, by who?