If an extraterrestrial visited Earth, and made contact with you, what proof would you need to believe they were genuinely not from this planet?

Do they look like human beings?

A drivers’ license issued by the DEV, with photo ID, is considered to be legal proof in most cases.

A better cover story as there are no planetary systems in the Orion region.

Show me their third eye.

Show me their ship.

I’m not sure there is a list of things that I could provide in this post. There are some general guidelines, because some of the details of this alien’s claims would require more evidence. For example, as @ANef_is_Enuf asked, if the alien looked like a person there would need to be some explanation and evidence of why/how this could be.

Overall, I don’t think there would even be a level of evidence that I would accept if it was merely provided to me. I agree with Sagan’s “Extraordinary claims require extraordinary evidence”. The evidence would need to be evaluated by other scientists from various disciplines. Then, we would need their data to be published and peer-reviewed.

@ANef_is_Enuf Spot on, you could not detect them on the street from an Earthling.

@DrBill A better cover story as there are no planetary systems in the Orion region. There concept of the Orion system could be vastly greater in size or deeper. We only have one view from a zillion miles away. Or their Orion system could be something entirely different.

@marinelife Show me their third eye. If they look so much like humans they can walk among humans and not be detected, the would have no “third eye”.

@tom_g Show me their ship. They show you what looks like a craft. How big does it have to be and how do you know it is not just a giant prop?

The evidence would need to be evaluated by other scientists from various disciplines. The most advance test humans could come up with would seem very crude to them, what if they are not incline to subjecting themselves to such primitive, at least to them, test? Then if they have been observing, they know what the government would do if they revealed they have been here. Do I hear SEAL team 6 lurking about?

I’ve been living among the humans for years… no-one’s ever asked me for proof.

Open their mouths & stick out a penis in place of a tongue. If this dick then proceeded to talk to me, i’m gonna be convinced they’re not of this earth.

@Hypocrisy_Central – You attributed @marinelife‘s “Show me their ship.” to me above.

@Hypocrisy_Central: “The most advance test humans could come up with would seem very crude to them, what if they are not incline to subjecting themselves to such primitive, at least to them, test?”

Then ignore them.

They never mention “tax” or “taxes”

@Hypocrisy_Central How do you know that they don’t have a hidden third eye?

As for ship, size does not matter, but they would have to show me it operational. I should have said take me for a ride in your ship.

I think I’d need to see them perform actions that defy the physcial laws as we know them. And they’d probably exhibit an extraordinary disinterest is politics, religion—all that stuff we get so worked up about ;-)

A navigation station.
An anatomy book (pics or it didn’t happen!).
A first aid kit.
Books, maps, star charts and a calculator.

A birth certificate.

If they are genetically similar to humans, then I would need to see some technology that was obviously wayyyyyy beyond ours. Like showing an iPad to someone in the 1500’s. Something inconceivably advanced.

Even if they were to show me advanced technology from their home planet (obviously they’re technologically ahead of us if they could get here to begin with) I probably wouldn’t be able to tell that it wasn’t from here (what’s the difference between a blackberry and an iphone again?), so I’d want to see their transportation. Maybe a convincing book on their planet, some pictures. Some kind of birth certificate or license if they have them where they come from.

@marinelife I should have said take me for a ride in your ship. I thought the reason you didn’t ask that was (1) If they are thought of as a nut job their contraption might blow up with you in it. (2) If they were real and you were on the ship, if they decided to leave, got chased off by the air force, wanted to take you back home to make a pet or a meal out of you, there would be no escape.

@picante I think I’d need to see them perform actions that defy the physical[sic] laws as we know them. Elucidate please, like transportation, levitation, using a energy beam weapon to hack down a tree, etc?

@CWOTUS @martianspringtime Books, maps, star charts and a calculator. A birth certificate. If the FBI and CIA can fake documents that would fool most experts, you think they could not do better? If it were real, how would you know it was real? If it was from Earth, it could have been faked, or they could have been smart enough to figure a way to get the real documents issued to them.

@Hypocrisy_Central, sorry for the typo—yes, I meant “physical laws.” And the suggestions you’ve made seem reasonable. They’d need to do something that really distinguishes itself from a magic act or an optical illusion. Levitation done as Criss Angel or David Blaine perform the stunts won’t cut it with me—but levitating themselves to a great height (maybe while I hang on) might be impressive.

If they could summon the rain to end our (Texas) drought, that would be convincing. If they could restore my faith in humanity, that would go a long way, too.

This is actually a really good question. I’m shocked I was the only one to GQ it.

I agree this is an excellent question.

I suppose if I needed to verify their alien status, I would try comparing their biological and sociological responses to the behavior of people here on Earth. I’m sure they have different metabolisms, different breathing patterns, different pulse rates, etc. Their movements would be different in subtle ways. And although someone can fake social awkwardness and ignorance of cultural norms, I believe their reaction would be different than someone who truly does not know. I would think that someone who is good at “cold reading” could tell if they were nutters, scammers or aliens.

Then again, as long as they aren’t causing trouble, they can study whatever they like, regardless of planet of origin.

If they looked like my alien friend Gort, and blurted out “KLAATU, BARADA, NECTO.”

http://theawesomer.com/photos/2008/11/112708_gort_t.jpg

Seriously, I think if they had the appearance and composition of something that I’ve never seen before here on earth, and if they acted “un-animal-like” and more on the “cosmic” or “supernatural” side. Then I’d be thinking “Omg, this thing, this “being” is not an animal, nor is it a human!”