A leading UFO expert has warned that aliens “don't come in peace” after spending 45 years investigating potential extraterrestrial sightings.
Malcolm Robinson has written 10 books on aliens and described what he thinks they look like.
One of the UK's leading extraterrestrial specialists, Robinson has researched dozens of alien incidents over the decades and claims they have carried out abductions.
Although many sightings are explainable, he says that there are also several incidents over the years that are still not fully understood.
And Robinson has warned that aliens “have an agenda”, although it is not yet clear what it is.
"Whilst a large proportion of UFOs can be explained away as having natural explanations, only a few remain, and it is to that small one percent that I and my colleagues worldwide are trying to get to the bottom," Robinson told the Daily Star.
"What is in no doubt, is that the UFO enigma is real, very real, it has been with us throughout time.
"We see this in Renaissance paintings and old cave paintings, these strange shapes and entities."
Asked what aliens might want from us mere humans, Robinson responded: "They have an agenda for sure - we can but speculate.
"I wouldn't say they are peaceful, due to the thousands of UFO abductions worldwide."
Robinson became immersed in the world of UFOs at the age of 20, when he tried to prove all sightings were nonsense - and failed.
Since then he has given lectures in the UK, Europe and America and has discussed his theories with the likes of Amanda Holden and Steven Spielberg.
He also founded Scotland's oldest current UFO and paranormal activity society, Strange Phenomena Investigations, in 1979.
When asked what he thinks aliens look like, Robinson said the most commonly-reported sightings aren't too dissimilar from the kinds of creatures we're used to seeing in films and TV.
"Witnesses state that they are seeing what we call 'Greys'," he explained.
"[These are] small childlike creatures, about three to four feet in height with bluey-grey translucent skin, large pear-shaped heads with inky black wrap-around eyes. No sign of any genitalia."
His many years of investigation have also led him to unpack a number of dramatic incidents, including Scotland's first-ever alien abduction, which allegedly saw Edinburgh residents Garry Wood and Colin Wright carried away on August 17, 1992, in what is now known as the 'A70 Incident'.
Writing about the incident for one of his best-selling books, Robinson described: "[The pair] were subjected to an astonishing and frightening experience which has stayed with them to this day."
The pair had been driving on the A70, described as a "desolate stretch of road" when they were confronted with a "two-tiered disc-shaped object which looked decidedly out of place" hovering about 20 feet above the surface of the road.
The men sped away and believed they had escaped, but lost about half an hour's worth of memory from the drive and, days later, began experiencing headaches.
It was then that Robinson became involved, researching the case and subjecting the pair to hypnosis to better understand what had happened that night.
"That hypnotherapist was Helen Walters, a dear friend of mine and someone who would treat both Garry and Colin with the utmost care," he wrote.
Under hypnosis, both men recalled seeing three small "entities" who took them into the flying black object and kept them there for some period of time.
"Both Garry and Colin are left feeling bemused by what happened to them," Robinson wrote.