For decades people have gazed up towards the space skies, wondering if we’re alone in the universe.
Some are convinced there’s life on other planets, while others aren’t so sure.
According to a recent study, half of us believe there will be an Independence Day-style attack in the next 50 years.
The research also astonishingly found that 71% of the 2,000 adults quizzed believed that aliens are currently living among us.
At the very least, there’s enough evidence to get even the biggest sceptics giving a second thought.
Over the past half a century, there have been enough incredible UFO and alien sighting claims to strengthen people’s will to believe there could be life out there in space and even here on Earth after all.
Here, we look at six alleged alien encounters that rocked planet Earth…
1947 flying saucer
Search-and-rescue pilot Kenneth Arnold reported seeing bizarre-shaped objects in the sky during a routine flight.
In his report, he said: “There were saucer-like things…flying like geese in a diagonal chainlike line”.
He claimed to have seen nine of the UFOs, which were racing across the sky at 1,000mph, near Mount Rainer in the US state of Washington.
Within weeks of the report, numerous UFO sightings were reported in 40 states.
Roswell UFO incident
In June 1947, ufologists claim a flying saucer smashed into the New Mexico desert and that the US government covered up the incident by quickly retrieving the spacecraft and taking the alien pilot to a secret military base.
Decades later, Ray Santill – who produced a 1995 hoax alien autopsy film – claimed to be in possession of actual photos of the retrieved extra-terrestrial.
The snaps showed the mysterious creature on an operating table, according to Mr Santill.
“Let me just be clear. I was not there in 1947, so I can’t say for sure if it is an alien, but it is the original camera footage.”
1952 Washington DC UFO
Over several months there was a spate of UFO sightings in the skies of the US capital.
In what became known as “the Big Flap”, multiple newspapers in the US reported credible sightings by bystanders and even radar operators.
The most-compelling account came from Edward Nugent, an air traffic controller at then Washington Airport who noticed flying objects on his radar, despite there being no scheduled flights.
He later said: “We knew immediately that a very strange situation existed…their movements were completely radical compared to those of ordinary aircraft.”
UFO historian Curtis Peebles said of the incident: “Never before or after did Project Blue Book and the Air Force undergo such a tidal wave of (UFO) reports.”
Rendlesham Forest sighting
On Boxing Day, US Air Force personnel stations at RAF Woodbride claimed they had spotted “lights” in the forest that surrounded the base.
Three years later, deputy base commander Lt Col Charles Halt released a memo which included a drawing of the apparent UFO that had been spotted.
The picture said there was a large object in the sky that was flashing red and orange, which was surrounded by at least four smaller craft that blinked blue lights.
But, researcher Dr David Clarke, of Sheffield Hallam University, told BBC News: “It may have been a lighthouse. It may have been some natural phenomena.”
Scientists at Texas Tech University were out in the town of Lubbock when they saw lights flying above them, racing at high speed.
In the following days, there were more cases of sightings and photos taken of the bizarre phenomenon by Carl Hart Jr were published in the famous Life magazine.
An investigation into the incident concluded the lights were caused by birds which reflected the shine coming from new street lamps below.
But, many who saw the bright objects refused the official explanation and argued that the lights were moving much faster than birds.
Tehran case of 1976
On September 19, Iranian’s in the country’s capital Tehran alerted police and military personnel after they saw bright lights in the sky.
An F-4 fighter jet investigated the area around the city and the pilot claimed to have seen a UFO releasing a “glowing object”.
At first, the pilot believed the UFO had sent out a missile and prepared to fight back before his aircraft started to malfunction.
He then spotted a second object that left the main UFO that went directly towards the ground before heading back to base.
An official report issued by the Government concluded the F-4’s equipment did not malfunction and that there was a meteor shower that night, which could have accounted for the lights seen in the sky by civilians.