Scanning Mars for ancient oceans through seismic waves, scientists found one stretching thousands of miles beneath the surface, but not the kind anyone expected since it formed from cooling molten rock pooling silently across an entire hemisphere

Mars has long been cast as a geological afterthought — a cold, quiet world where volcanism was modest, short-lived, and far less dramatic than the churning processes that shaped Earth. Without plate tectonics, scientists assumed its crust formed simply, leaving behind little more than isolated volcanoes frozen in time. But seismic data collected from deep ... Read more