Is there a top human knowledge Wikipedia articles compilation? Like what we must save in a time capsule?

Question

...or in other words: an Alien comes and wants to learn the essential about us, the planet, our science, culture, history, achievements, arts... (assume he/she/that can read english already)

Answer 1

I don't know about Wikipedia, but Yahoo has a new time capsule project
http://timecapsule.yahoo.com/capsule.php
You can read other people's contributions or submit your own.