Mars – dusty, dry, and desert-clad – was once so rich in water it had not just lakes, but oceans, according to a new study.
Observations using ground-penetrating radar have revealed underground features consistent with beaches on the red planet, 4 billion years ago. It’s some of the best evidence to date that Mars was once so soggy as to host a northern sea.
The research team has named that sea Deuteronilus.