It has been exactly 50 years since Erich Von Daniken hypothesized in his controversial work Chariots of the Gods that the Bible proves ancient man met with aliens, adopting new technologies from extraterrestrials. Many Biblical prophecies are, according to Von Daniken, UFO sightings described in Biblical terms. His startling theory sought to challenge the way we see ourselves in the universe and in relation to God.His "theory" (i.e., notions) is not controversial, nor is it "much-contested." It is completely bogus from beginning to end and no professional historian or archaeologist bothers to contest it (except maybe occasionally on a blog) because it is not a responsible theory.
Though controversial and much-contested, his theory (called paleo-contact) is popular with his 62 million readers. Von Daniken based this theory on structures and artifacts that represented higher technological knowledge than was presumed to have existed at the times they were manufactured. He cites depictions in cave drawings, clay tablets, and other archaeological findings to support his theory of alien contact.
Nevertheless, it is all very entertaining and his notions have caught the attention of many, a few of whom have been inspired to go on to do serious archaeology, history, and philology. As I have mentioned before, I am one of them. So peace be upon him. If he comes up in casual conversation, be patient and use it as a teaching moment.
Some past posts that discuss von Däniken and his goofy ideas are here, here, and here, and he is also mentioned here, here, here, and here.