UFO sighting: Alien hunter thinks he found an 'underground city' on Mercury built by ETs

The supposed alien structure measures more than three miles across if the conspiracy theory is to be believed. According to prominent UFO researcher and self-titled expert Scott Waring, the

bizarre discovery is "100 proof" aliens are real. Mr Waring took to his blog UFO Sightings Daily to share official NASA photos snapped by the MESSENGER spacecraft.

The black-and-white images appear to show a mound or crater with a roughly square-like cavity in the centre.

In Mr Waring's opinion, the square hole is the entrance to a secret city just beneath the planet's surface.

He said: "I found a white fungus structure, but next to it is a massive square entrance. The entrance is dark from the shadowy depth.

"The map ruler says this square entrance is 5km by 5km. That's big enough for spaceships to enter and exit.

READ MORE: Life on Mars: 'Martian crops' grown in boost for colonisation

"This must be one of the entrances to an underground city.

"This entrance and the structure near it are 100 percent proof that aliens exist and thrive on Mercury.

"Now you know why NASA tries to keep the existence of aliens secret.

"There is alien tech and bases on every planet and moon in our solar system."

Mr Waring went on to suggest his supposed discoveries are "easy pickings" for any country with the means to launch a retrieval mission.

We use your sign-up to provide content in ways you've consented to and to improve our understanding of you. This may include adverts from us and 3rd parties based on our understanding. You

can unsubscribe at any time. Read our Privacy Policy

The UFO hunter also shared his findings on YouTube where it was analysed by his followers.

One viewer said: "It's definitely an entrance. We've seen entrances like this on most of the planets, their moons, our Moon and very good chance they are in the Earth's interior.

Another person said: "There's structures all through the solar system just think what's outside our solar system."

DON'T MISS...Alien archway on Mercury - 'Advanced far beyond humanity' [PICTURES]Life on Mars breakthrough: 'Martian crops' grown in boost for colony [INSIGHT]UFO sighting: Mystery lights

stream over Colombia in ET claim [VIDEO]

But not everyone was convinced by the bizarre claims, with one person saying: "Underground city? You cannot be serious."

There is also no evidence to back claims life exists on Mercury, or anywhere beyond our planet.

According to NASA, the conditions on the innermost planet of the system are simply too harsh for life to thrive.

The space agency said: "The temperatures and solar radiation that characterize this planet are most likely too extreme for organisms to adapt to."

The most likely explanation for Mr Waring's so-called discovery is an effect known as pareidolia.

Pareidolia, which is a form of apophenia, describes the brain's tendency to see recognisable shapes and patterns where they do not exist.

For example, pareidolia can cause people to see faces in clouds or car bumpers.

NASA said: "Pareidolia is the psychological phenomenon where people see recognizable shapes in clouds, rock formations, or otherwise unrelated objects or data.

"There are many examples of this phenomenon on Earth and in space."

See today's front and back pages, download the newspaper, order back issues and use the historic Daily Express newspaper archive.