New Delhi: Venus, Earth and Mars all started out as similar terrestrial worlds assembled around a newborn star about 4.5 billion years ago. However, the three planets went down very different evolutionary trajectories, even though all three were believed to be habitable in the infancy of the Solar System. Venus is a hothouse with a runaway greenhouse gas effect, Earth has an oxygen-rich atmosphere, a protective geomagnetic field, and liquid water on the surface, while Mars is an arid and cold desert. In the past, scientists believe Mars was habitable too, and also had liquid water flowing on the surface, with any........

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