With terraced mountainsides reminiscent of canyons on Earth and channels that appear to have been etched by receding water, Arabia Terra on Mars preserves striking evidence of cataclysmic tsunamis that may have happened around 3.4 billion years ago. Some scientists speculate that two large meteors impacted the same region of the planet separately, perhaps several million years apart, leaving behind the telltale features that appear in the image. However, others think that Mars had lost most of its liquid water hundreds of thousands of years before the meteor impacts, and thus the topographical formations could not have been created by tsunamis. So, which interpretation will prevail?