Either Americans don't trust their government, or they have a lot of respect for aliens' stealthiness.

Thirty-six percent of Americans think aliens have visited Earth, and almost 80 percent believe the government has kept information about UFOs a secret from the public, a new survey finds.

The survey, conducted ahead of National Geographic's new series Chasing UFOs, asked 1,100 Americans 18 and older for their extraterrestrial opinions.

As it turns out, the idea of aliens and UFOs isn't that farfetched to most Americans.

Here are some of the survey's most surprising findings:

-More than three quarters (77 percent) of those surveyed believe there are signs that aliens have visited Earth, and over half (55 percent) think Men in Black-style agents threaten those who report seeing them.

-More than a third (36 percent) believe aliens have already visited.

-Eighty percent believe the government has hidden information on UFOs from the public.

-Nearly two thirds (65 percent) think President Obama would be a better leader than Mitt Romney if an alien invasion were to happen.

-When it comes to superheroes, 21 percent think the Hulk would be their first call in an invasion, 12 percent would call Batman, and 8 percent say Spider-Man's their guy.

-In the event of an invasion, the respondents themselves would leave the fighting to superheroes and presidents, it seems--about a fourth said they would try to befriend the aliens, 13 percent said they would hide indoors, and just 5 percent said they'd try to "inflict bodily harm" on the invaders.

-Just 17 percent of those polled did not belive in UFOs; about half said they were unsure.

Seth Cline is a reporter with U.S. News and World Report. Contact him at scline@usnews.com or follow him on Twitter.