Hold on to your tin foil hats, because this is a good one.
Alien hunters have found what they claim to be an unexplained shadow on Mercury, which is caused by a large structure.
In a video, posted on YouTube by Secureforce10, viewers can see a black rectangular ‘structure’ in a Nasa photo of the Mercury surface which conspiracy theorists claim could be an entrance of some kind.
The object was first spotted in 2012 by UFO Sightings Daily, where Scott C Waring reported it as a ‘doorway’ more than three miles long.
But in the new video, from alien-hunter Tyler Glockner, it may not be a doorway but a huge rectangular monolith.
‘I took a really good look, it became clear to me that this is not an entrance at all. In fact, it’s something much more magnificent.
‘This is a shadow … where is the shadow coming from?’
‘That my friends, is this large, long rectangular object, monolith-looking structure towering up above the surface.’
The 19-minute long video has already been viewed more than 260,000 times.
In the original Nasa image, captured by the Messenger probe, the crater left of centre is approximately 26 miles (42 kilometres) in diameter.
According to Glockner, the angle of the sun casting shadows on the northern walls of the craters means the black rectangle is a shadow cast by a standing structure.
‘What we have here is a very tall, rectangular object…that is standing up over the surface, casting this perfect shadow,’ he explains.
Zooming in to the image, he claims: ‘whatever this object is, it has to be miles, likely. But it is a structure.
Citing his experience of finding previous structure from other images, Glockner adds: ‘I know how shadows work as well as [how] natural formations react to the sunlight.
‘As you guys are seeing, this is clearly a large rectangular building, the top and front of it is being hit by the sun, the back of the structure is in darkness and we have this very long shadow being cast down on the surface behind it.’
Mercury is the closest planet to the sun and the smallest of the eight planets.
Temperatures on the surface can swing wildly from lows of -173°C (-280°F) to blistering highs of 427°C (800°F).
The days are long but the years are fast. The planet rotates once every 176 Earth days and orbits the sun once every 88 Earth days.