An astronomer at the U.S. Naval Observatory has developed a hypothesis to explain the unique shape and terrain of Mars. He suggests both are due to a long-lost moon. Michael Efroimsky has published a paper outlining the hypothesis on the arXiv preprint server. An astronomer at the U.S. Naval Observatory has developed a hypothesis to explain the unique shape and terrain of Mars. He suggests both are due to a long-lost moon. Michael Efroimsky has published a paper outlining the hypothesis on the arXiv preprint server. Planetary Sciences Phys.org – latest science and technology news stories