The faint but distinctive dot which can be seen on the horizon of the Red Planet was taken by a device on the $2.5 billion robot called its Hazcam and relayed by the Mars Reconnaissance Orbiter back to Earth.

However, two hours later when the satellite made another pass over Curiosity, the rover sent another batch of images that revealed that the blotch had eerily disappeared.

The Internet was instantly awash with theories as to why the two photographs would be different, especially as the rover, which is the largest spacecraft ever sent to another planet, landed on its own with no direct control from NASA mission control.

Furthermore, the rover was acting autonomously, meaning that scientists did not command the robot to photograph the exact views containing the blotch.