At first glance, a photograph of Mars released by NASA appears to show a doorway carved into the rock.
The grainy image, taken by the Curiosity rover last week, clearly shows a rectangular gap in the rock and has, perhaps inevitably, given rise to conspiracy theories that point to it as evidence of alien life on the red planet.
As long as people have looked up at the sky, we have seen things that are not really there – whether it is images in constellations, a face on the moon or a “mysterious hut” discovery by Chinese researchers that turned out to be a boulder.
And the simple explanation for the “door” on Mars is actually in the photograph itself if you look closer, researchers have said.
It shows evidence that the function was formed by “normal geological processes”, Professor Sanjeev Gupta at Imperial College London told The Daily Telegraph.
A deep crack or crack is visible inside the “door”, indicating a crack in the rock – something that happens on both Mars and Earth and could have taken place at any time during the last hundred million years.
“The crack is a crack and they are abundant on Mars and Earth – no need for Martian earthquakes to produce them,” said Professor Gupta, who has worked on the Curiosity mission with NASA.
“There is nothing at all strange in the picture – these are just normal geological processes.”
Perspective also comes into play – NASA says that the crack only seems to be a full-size door because the image is extremely zoomed in.
The rift is actually a small crack in a rock, a spokesman for Snopes, a fact-checking website, explained.
“The team’s researchers emphasized how small it is,” they said, about 30 centimeters by 45 centimeters.
According to the researchers, “there are linear cracks throughout this slab, and this is a place where several linear cracks happen to cut,” they added.
The good news is that the Curiosity rover continues its search for life on Mars, or at least a sign that life once existed there.
NASA rover landed in the Jezero crater on 18 February last year – together with the Ingenuity Mars helicopter – and has collected samples and sent back photos.
It will spend at least two years exploring the area.