Planet Quest is a pretty amazing multimedia timeline of space exploration that begins at 500 B.C. In addition, it provides audio support for the text. I learned about it from Richard Byrne.
I’m tentatively adding it to The Best Sites For Learning About Planets & Space. The reason I’m only doing so “tentatively” is because even though it’s a wonderful site, the vocabulary is a bit advanced — perhaps too advanced for many English Language Learners.