Comet Siding Spring traveled from the most distant region of our Solar System, the Oort Cloud. It made a close approach to Mars on October 19, 2014, within about 139,500 km of the planet. Dust from the comet impacted Mars and was vaporized high in the atmosphere, producing what was likely an

“Our oceans were always here. We didn’t get them from a late process, as was previously thought,” said Dr Adam Sarafian, a researcher with the Woods Hole Oceanographic Institution and the first author of a paper published in the journal Science. One hypothesis was that the Earth and other