Mars, the fourth planet from the Sun, was among the first bodies in the Solar System to be viewed through a telescope. Early astronomers could see faint surface features along with evidence of changing seasons and speculated about an advanced Martian civilisation. NASA’s Mariner and Viking probes in the 1960s and 1970s found a cold, apparently lifeless planet with intriguing geology that hinted at past surface floods. More recently, six-wheeled rovers have confirmed that water ice exists below the surface and looked for evidence of past microbial life.

Photo: Victoria Crater on Mars taken by the Mars Reconnaissance Orbiter probe (NASA/JPL-Caltech/University of Arizona/Cornell/Ohio State University)

NASA

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