Scientists have long suspected that Mars was once warm and wet in its ancient past. The Mars Ocean Hypothesis says that the planet was home to a large ocean around 4 billion years ago. The ocean filled the Vastitas Borealis basin in the planet’s northern hemisphere. The basin is 4–5 km (2.5–3 miles) below Mars’ mean elevation.
A new topographic map of Mars reinforces the hypothesis and adds more detail.Continue reading “Scientists Piece Together the Shoreline of an Ancient Ocean on Mars”