While the world is divided over whether 'that dress' is blue and black, or white and gold, Nasa has been involved in a colour controversy of its own. This time the debate involves Mars – the so-called 'red planet' – which conspiracy theorists believe is in fact more blue and green. They argue the space agency has manipulated the colour of images from Mars to appear red, orange and pink, in what they claim is an attempt to mask life on the planet. Scroll down for video . The debate has raged since the 1970s when Nasa's Viking 1 lander became the first spacecraft to touch down on the red planet/ Its initial images revealed what appeared to be a blue sky (right), but in reality Nasa says the planet has a red/orange sky. On the left is a processed image of what Nasa believes Mars to look like . The sky on Earth is blue because of a phenomenon known as 'Rayleigh scattering', in which blue particles of light are scattered around by the atmosphere. On Mars, the reverse effect takes place. The dust in the atmosphere scatters the red particles of light, makes the sky appear red. Nasa claims the sky appeared blue because Viking's filtered images still had to be calibrated with the right colour balance. The debate has raged since the 1970s when Nasa's Viking 1 lander became the first spacecraft to touch down on the red planet, according to a report by Alan Boyle in NBC News. Its initial images revealed what appeared to be a blue sky, similar to that seen on Earth, raising hopes that there may be Martian life. Viking team member Carl Sagan announced at a press conference soon after: 'Despite the impression on these images, the sky is not blue...The sky is in fact pink.' The sky on Earth is blue because of a phenomenon known as 'Rayleigh scattering', in which blue particles of light are scattered around by the atmosphere. On Mars, the reverse effect takes place. The dust in the atmosphere scatters the red particles of light, makes the sky also appear red. Nasa claims the sky appeared blue in the first Martian images because Viking's filtered photographs still had to be calibrated with the right colour balance. Nasa sometimes uses different filters to depict Mars. The left image shows Mars as seen by the Hubble Space Telescope in July, 2001. Centre is Mars as seens by the Hubble Space Telescope in March, 1997. On the right is the red planet as seen by the Mars Global Surveyor in February, 2006 . The left version is the raw, unprocessed view as it is received directly from Mars. The centre is a guess of the 'natural' colour that humans would see if they visited Mars. The right version shows the result of white-balancing, which interprets the scene as if it were viewed under Earthlike lighting conditions . But not everyone is convinced. Ron Levin, a researcher at Lockheed Martin stated in areport: 'An excess of red is found on all of the Martian blue and green panels. 'Such extreme illuminations are shown to be incompatible with the grey panels. 'It appears that the true raw image data have been modified prior to publication to convert the blue and green pixels to grey, rendering a grossly changed image.' Conspiracy theorists have made wilder claims, with one writing: 'The images were falsely reddened to make it appear there was no life, no green algae or lichen on the plane.' Today both the Opportunity and Curiosity rover have patches of colour attached to their instruments that are used in to adjust the reflected colour to a true likeness. Is this what Mars really looks like? A mosaic from Nasa's Curiosity rover shows Mount Sharp in raw colour. Nasa says raw colour is similar to the way the scene would look 'in a typical smart-phone camera photo' Pictured is the same scene after it has been given a white-balanced colour adjustment that turns the sky blue. Nasa sometimes does this to simulate Earth-like lighting, making it easier to analyse the geology . As a result, pictures of Mars are usually altered to provide a red and pink tinge caused by the iron-heavy dust that fills the atmosphere. But even Nasa admits this isn't an exact science. Colour balance is a highly subjective and no two spacecraft use the same exact filters. As well as this, people often perceive colours differently – as shown by the famous black and blue dress. To clear up the debate, Nasa usually releases a number of different types of Mars imagery, which include the raw file, unprocessed colour pictures and true-colour versions. To add to the confusion, the Curiosity rover recently found that the interior of Mars' rock 'Telegraph Peak' is in fact blue/grey. To add to the confusion, the Curiosity rover recently found that the interior of Mars' rock 'Telegraph Peak' is in fact blue/grey . Colour balance is a highly subjective and no two spacecraft use the same exact filters.As well as this, people often perceive colours differently – as shown by the famous black and blue dress .
In 1976 Nasa's Viking 1 sent back an image of Mars with blue skies . Nasa claimed image had yet to be calibrated with right colour balance . Some conspiracy theorists have questioned Nasa's calibration methods . Nasa admits it isn't an exact science and often uses different versions .