Odd-looking aircraft or lights hovering high in the sky at various times across the U.S. have prompted questions from space enthusiasts: if it's not a bird, plane or even Superman — then what is it? UFO sightings have soared in recent years, leading many to believe it's a sign of alien life.

Reports of UFOs have become so common lately people are starting to bet on when you're most likely to spot on next. Casino.org, an independent provider of online casino reviews and information, tracks the odds on its website. It even includes a history of mysterious spacecraft dating back to 1440 BC.

California alone has reported more than 23,400 UFO sightings since 1940, though the odds of seeing a strange flying object are highest in Wyoming and Vermont.

'UFO SPOTTED' OVER MYRTLE BEACH, DISTURBING ONLOOKERS

Whether you live in a state ripe for alien-like space vehicles or not, people who spot questionable objects in the sky are going to snap a picture or take a video — and there's a good chance the content will go viral. Here's a look at some bizarre "UFO sightings" that have spread online in recent years.

Myrtle Beach, S.C.

A photographer who was putting together a time-lapse video of a thunderstorm in Myrtle Beach, South Carolina, in August was shocked to discover mysterious lights hovering over the pier in the footage.

The video, which was first shared with UFO Stalker — a UFO-centric website, was posted to YouTube a month later with a caption that declared a "massive spaceship" was flying over the beach.

“I was taking the pictures off the edge of a long pier after dark, so there were no reflective surfaces around. I did not notice the objects until [I] returned home and checked the photograph and video,” the photographer, who has not yet been identified, wrote on the UFO sighting website.

Lake Norman, N.C.

A very shaky video of what many dubbed a UFO flying over Lake Norman in North Carolina went viral in late May.

"I was at work 2018 10:30 a.m it had been raining all morning. Rain finally stopped so we went w pick up a boat from [L]ake [N]orman.. When came around the corner I saw this thing sitting still very close," Jason Swing, who posted the video on YouTube on May 29, captioned the minute-long footage.

Critics questioned whether the curious flying object was simply a large drone or a blimp — with some noting a Goodyear Blimp was spotted in the sky following a NASCAR race.

The manufacturing company later confirmed they were the culprit.

"We don’t want to get in the way of a good story, but that’s definitely us," the Goodyear Blimp account wrote, according to the Daily Mail. "We left the Charlotte area 5/29 after covering the Coke 600."

Blue Hills Reservation, Mass.

UFO hunters got stranded for hours in the Blue Hills in Massachusetts in June 2017 after going out for a UFO-finding mission. The group of three was found several hours later, and they didn't come back empty handed.

Ramona DiFrancesco, a member of the group, told The Singular Fortean Society they spotted several UFOs while lost on the hills.

"We saw a couple. We saw some we've never seen before. We saw this one light, well, we saw these two ships that had these bright spotlights, and then we saw this weird orb thing that was like a spotlight sort of," DiFrancesco, then 18, told the paranormal organization.

The teen later showed a local news station a picture of the glowing object she captured.

International Space Station

A disc-shaped ray of light could be seen disappearing into space in a video uploaded by UFO conspiracy theorist Tyler Glockner in May 2017.

Glockner claimed in a video the mysterious burst of light was a UFO racing past the International Space Station "at a very high rate of speed," adding it was "as if it knew the camera was watching."

At the time, NASA didn't directly address Glockner's video but clarified the object was likely a "distortion in a lens" and did not signify the presence of extraterrestrial life.

Dayton, Ohio

A 13-minute YouTube video sparked rumors of alien life outside of a military base in Dayton, Ohio, back in May 2016.

A mysterious flying object was seen peeking out of the clouds near Wright-Patterson Air Force Base.

A couple who live near the base captured what they declared was a UFO from their home. The video clip eventually landed in the hands of the aforementioned Glockner, who called the sighting "mind-blowing."

"There is no doubt in my mind this is either an alien craft or a very very strange drone - which I highly doubt," he told the Mirror. "[It could also be] a back-engineered alien craft that's being tested by some black project over at Wright-Patterson Air Force Base."

Fox News' Chris Ciaccia contributed to this report.