James Oberg worked at NASA mission control in the late 1990s before becoming a space journalist and historian.
A few years ago he was bitten by the UFO bug. So what does he have to say?
The first people to be disappointed by his revelations will be alien conspiracy theorists hoping he was about to lift the lid on the alleged cover up by NASA of the existence of ETs.
Instead, Mr Oberg has spent months sifting through popular online UFO cases, debunking them using science.
His conclusion revolves around something he calls “space dandruff” – or people misunderstanding what space travel would actually looks like.
Mr Oberg says he does not want to humiliate genuine believers, as that is just like “stomping on dormice.”
Instead, he hopes he can work out what really happened during each popular sighting and why so many people believe they are aliens.
He said: “Our human senses are so used to focussing on relatively slow-moving objects, as well as certain light and atmosphere conditions, that when things change, our brains get confused.
“Our sensory system is functioning absolutely perfectly for Earth conditions.
“But we’re still a local civilisation. Moving beyond our neighbourhood has been visually confusing.”
Some of the UFO cases held up as the most compelling result from claims by NASA astronauts that they allegedly saw UFOs during a space mission.
But these are invariably followed by claims of a cover up and that NASA forced them to to keep silent about the sighting.
Mr Oberg said on his website: “I’ve had enough experience with real spaceflight to realise that what’s being seen in many videos is nothing beyond the norm from fully mundane phenomena occurring in unearthly settings.”
Over the past 12 months, there have been a glut of alleged UFO sightings on the live stream of the International Space Station (ISS).
Many were reported, and some already debunked, on Express.co.uk, as lens flares, when light reflected inside the camera is fired back out onto the resulting camera or video image.
Mr Oberg said many of the other ISS sightings were space dandruff.
These are bits that have fallen off space vehicles during flight, like ice flakes, paint chips, or fragments of insulation.
He said these tiny pieces of litter are different to space junk, because they don’t pose a real threat to any spacecraft.
Our sensory system is functioning absolutely perfectly for Earth conditions. But we’re still a local civilisation. Moving beyond our neighbourhood has been visually confusing.
One major event, that took the net by storm last year, was a flare of light across a Californian night sky.
In December locals were freaked out when the white streak shot across the night sky.
However, Mr Oberg pointed out it has since emerged it was a planned, unarmed missile test by the US Navy.