Alien chasers hope the annual event will pressure world leaders to release top secret flying saucer files, and even admit that a massive cover up over alien life has been going on for years.
UFO-ers have been keeping their eyes firmly on the skies to celebrate the global fascination with the flying saucer.
The event is now in its 17th year.
According to the World UFO Day website, it is dedicated to “raising awareness about the undoubted existence of UFO’s and with that intelligent beings from outer space.”
The website is also part of a campaign to get international governments to “declassify” their so-called confidential “X-Files” on UFO sightings throughout their history.
And, it is convinced something might be about to happen.
An article to coincide with this year’s event said: “We at World UFO Day feel something is in the air.
“Since December 21st, a lot of interesting turns have been made by the UFO community.
“The image of UFO believers has made a shift. People around us are opening up to a truth that has been there all along.
“Is it time for the truth about UFOs to come out in 2017?”
The website believes President Donald Trump could be the key.
It added: “When Trump first became President there were many hopeful signs that his push for more transparent and accountable government would translate into greater openness where the truth would finally come out about UFOs and extraterrestrial life.
“Whistleblowers were ready to come forward to testify about a host of illegal government activities if they were given protection to reveal their secrets.
“This culminated in the belief that disclosure of extraterrestrial life was imminent early in the Obama administration.
“Four years later, those early hopes look positively naïve.
“Government transparency did not open up national security archives to researchers, and whistleblower protection did not happen after all.
“The Trump administration went on the record to disavow any interest in investigating claims that the Roswell crash really involved otherworldly UFOs.
“There was no disclosure of extraterrestrial life visiting our world.
“But what has changed, four years after Obama’s first Presidential election, is that the world is better prepared for accepting that extraterrestrial life exists?”
The website said a recent survey found 80 million Americans, 36 percent of the US population, believe UFOs are real.
One in 10 respondents even said they had witnessed an alien spaceship.
A separate Express.co.uk survey found that 36 percent of people asked who is most likely to reveal the existence of aliens thought it would now be Donald Trump.
A whopping 37,800 people responded to our online survey, with 13,608 saying they felt Mr Trump could be the disclosure president.
There were 9,450 who thought it would instead be Russian President Vladimir Putin, and the same figure said “no one, because aliens do not exist.”
There were 4,536 people who felt a retired Barack Obama would do it and just 378 people thought it would be Theresa May and the same amount felt German chancellor Angela Merkel might come through.