In most cases, the photos only show odd rock formations and other unusual shadows.
But there is no concrete evidence to support the claim intelligent aliens exist anywhere beyond Earth.
There is, however, an explanation for why so many UFO hunters and conspiracy theorists see spaceships and aliens on the Moon and Mars – pareidolia.
Pareidolia is a peculiar effect that affects everyone and causes the brain to see recognisable patterns where they do not exist.
In its simplest form, pareidolia kicks in when people see smiling faces in car bumpers or animal-like shapes in clouds.