The chance that extraterrestrials hailing from deep within the incomprehensibly vast regions of outer space have discovered and visited planet Earth may be infinitesimal.

But it's not zero.

Witnesses have for decades comes forward to share their alleged encounters with strange flying objects and even otherworldly beings themselves, only to often be ridiculed and dismissed. The specter of flying saucers and little green men has long been a topic relegated to the realm of pop culture at best, and hokum at worst.

Yet for better or worse, UFOs have increasingly entered the mainstream in recent months as military whistleblowers and others come forward with accounts that lend credibility to a long stigmatized concept.

Now, witnesses once made to feel like crackpots are sharing what they believe are sightings of UFOs in "Encounters," a docuseries premiering Wednesday on Netflix. Across four episodes, the series will rely on firsthand accounts to explore the evidence (or lack thereof) that we may not be alone in the universe.

"Most people would say the question is, like, 'Are we alone,'" one person says in the trailer, released earlier in September. "I think the question is, 'Who are we?'"

Watch the trailer:

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What is 'Encounters' about?

The upcoming docuseries is the latest in recent years to explore UFOs in the wake of a 2017 article in the New York Times that first exposed a shadowy Pentagon program to study what the government officially refers to as UAP, short for unidentified anomalous phenomena.

Directed by Yon Motskin, each episode of the series produced by Stephen Spielberg's Amblin Television, Boardwalk Pictures and Vice Studios explores a separate report of a mass sighting in a different part of the world.

Billed in Netflix press materials as a "detective story," "Encounters" relies on both firsthand accounts and also the testimony of various scientists and military officials to delve into reports of suspected extraterrestrial phenomena. The four episodes feature accounts of strange lights in the sky in 2008 over small-town Texas; Cold War-era submersible crafts lurking near a coastal Welsh village; a non-human intelligence reportedly interfering in 2011 with the operations of a nuclear power plant in Japan; and an alien encounter in 1994 experienced by schoolchildren in Zimbabwe.

"UFOs, UAP's, non-human intelligence, whatever we might call it — I didn’t before but now I think it exists," Motskin told Netflix. "It could be non-human intelligence from far away, or from the past or future, or even us from the future. But I believe ‘the phenomenon’, as it’s called, has been around for a long time."

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Why is the docuseries relevant now?

Public interest in UFOs has been building since July when three former military officers testified in front of Congress about mysterious objects sighted by Navy pilots, as well as a clandestine program to retrieve and study downed spacecraft.

The claim of the crash retrieval program came from former U.S. Air Force intelligence officer David Grusch, who testified before a House Oversight subcommittee that his country has been aware of “non-human” activity since the 1930s. Though he was constrained in presenting hard evidence about alleged classified programs, Grusch claimed to have been informed that the Pentagon has been able to obtain and study not only interstellar crafts, but the bodies of extraterrestrial pilots themselves.

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The Pentagon has repeatedly denied that such a program exists.

Since then, the Pentagon's office to investigate UFOs unveiled a website where the public can access declassified information about reported sightings and soon make reports of their own.

And earlier this month, NASA released the findings of a long-anticipated report on UAP while appointing a new chief of UFO research. The announcement came on the heels of Mexico's first ever UFO hearing that featured wild testimony from a UFO researcher presenting what he alleged were the mummified bodies of ancient aliens, a claim that has been disputed by scientists.

NASA scientists and other astrophysicists acknowledge the phenomena of objects sighted in skies flying in ways believed to be beyond the capabilities of known human technology, but also caution that otherworldly explanations for UFOs aren't likely even in the absence of a natural one.

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Eric Lagatta covers breaking and trending news for USA TODAY. Reach him at [email protected]