So-called Nibiru truthers claim Nasa is part of a conspiracy to "hide the truth" from the general population while the 'global elite' escape to the safety of secret underground bunkers.
Nibiru, sometimes referred to as Planet X, is a hypothesised planet on the edge of the solar system that orbits the sun every 3,600 years.
Conspiracy theorists believe the gravitational influence of Nibiru disrupted the orbits of other planets in the solar system hundreds of years ago as the object ringed the sun.
They claim the next disruptive passage could happen at any time, with the planet predicted to either collide directly with Earth or trigger apocalyptic weather patterns across its surface.
Dr Morrison's comments were made during a podcast released by the Search for Extraterrestrial Life Institute (SETI) website.
It was part of the "Big Picture Science Radio Show", which broadcast an episode called "Skeptic Check: Nibiru! (Again!)"
When asked what would happen if Nibiru entered the solar system, Dr Morrison said: 'If a big object was coming into the solar system its gravity would perturb the orbits of the planets, and we would have detected that long before it came close to the Earth.
'The planet's orbits are very regulated, and, if some massive object came along every so often and came through the inner solar system, it would all be screwed up, the planets would not be coplanar.
"The moon would have been ejected, and obviously that is not the case."
However, Dr Morrison said it was pointless describing what would happen as "Nibiru does not exist."
Nibiru has been the focus of a host of conspiracy theories over the past twenty years, and the latest rumours originated from Planetxnews.com.
A team of conspiracy theorists behind the site followed the growing number of earthquakes and volcanic eruptions that have hit Earth in the last few months.
They claim the disasters were caused by the gravitational pull of Nibiru and that their frequency has risen as the planet's path brings it closer to Earth.
"Global seismic activity reaches a peak in the second two weeks of November moving into December 2017," claimed writer Terral Croft.
"The predicted backside alignment quake event is scheduled for November 19, 2017, when the Earth passes behind the sun relative to the Black Star [Nibiru]," he told the Express.
Back in September, Nasa was forced to publicly state that Nibiru does not exist in an attempt to quell doomsday fears.
"The planet in question, Nibiru, doesn't exist," the space agency said in a statement.
"Nibiru and other stories about wayward planets are an internet hoax. There is no factual basis for these claims."
"f Nibiru or Planet X were real and headed for an encounter with the Earth astronomers would have been tracking it for at least the past decade, and it would be visible by now to the naked eye.
"Obviously, it does not exist"
After Nasa's predictions rang true when the apocalypse didn't come on September 23, "Christian numerologist" David Meade, who first claimed Nibiru was on its way in a series of YouTube posts, clarified his story.
Mr Meade, who also writes for Planetxnews, said that the apocalypse has in fact been delayed, and was never predicted to arrive on September 23.
Speaking to the Washington Post, Mr Meade said the date only marks the beginning of the end of times.
'The world is not ending, but the world as we know it is ending,' he said.
Mr Meade used the "biblically significant" number 33 and his interpretation of the Bible's Book of Revelation to suggest that the legendary - and widely debunked - planet Nibiru would strike Earth on September 23.
The impact would set in motion cataclysmic events, according to Mr Meade.
Nibiru would strike 33 days after the total solar eclipse. In his analysis, Meade cited how Jesus allegedly lived for 33 years.
Despite a lack of evidence for the hidden world, which Nasa has previously stated is an "internet hoax", many people believe it is real.
The scientific community has repeatedly asserted that Nibiru does not exist.
