All you hardcore comics fans know that the origin of the Venom symbiote is from Marvel's first Secret Wars series of comic books. After battling the bad guys on the Beyonder's battleworld, his Spidey suit gets ripped beyond repair. So, Spidey uses some alien technology found on the piecemeal planet as a "costume maker". Unbeknownst to him, the alien symbiote was hiding inside waiting for just that opportunity to cleverly attach itself to a human host. Later back home, with the help of Mr. Fantastic, Peter figures out that its alive and needs to come off before becoming unattachable.
Since the comic book origin would be too much of a history to relate in the movie, we at comicbookmovie.com had theorized that the symbiote might have been brought back from space by astronaut John Jameson, already seen in Spidey 2--the son of J. Jonah Jameson. But lo and behold this pic has turned up on the web which seems to show a meteor hitting the earth, dangerously close to Petey's Moped!