Wave generation beyond Earth

In their otherwise excellent article, “How does the wind generate waves? ” (Physics Today, November 2021, page 38), Nick Pizzo, Luc Deike, and Alex Ayet missed an opportunity to note the interest and progress in that question as a physics problem beyond the narrow parameters of water and 1-bar air. Specifically, the possible presence of shoreline features on Mars—where transient paleoclimates may have allowed lakes and seas under a thin, carbon dioxide–rich atmosphere ¹ —and the present-day existence of liquid-methane seas on Saturn’s moon Titan under an atmosphere four times as dense as our own ^{2 , 3} have prompted planetary scientists to confront the topics laid out in the article and to sift through what aspects of the terrestrial paradigm are empirically specific to Earth. Extending wave mechanics to other environments and parameter regimes with different gravity and fluid properties fosters more fundamental understandings. Oceanography is no longer just an Earth science.