... Science Frontiers ONLINE No. 131: SEP-OCT 2000 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects The Earth Made Mars Different At the June, 2000, meeting of the Society for Scientific Exploration, R.A . Day presented a paper that: Itemized the many important ways n which Mars differs from the other inner planets and moons; Proposed a mechanism that might lave created these stark differences; and Identified the earth as the most likely perpetrator of this celestial catastrophism. Day's abstract follows: Mars has surface features that are not seen on inner planets or moons. These are hemispheric asymmetries, idiosyncratic surface fracturing, localized vulcanism, altitude differences, chains of pits, and the nature of dry river-like channels. Other features include extensive loss of an early atmosphere and liquid water. There is interest in the lower-altitude northern region, with its surface formed after the period of heavy bombardment, as a possible ocean basin. The evidence for this is very sparse: no river deltas, no river networks, little debris at the ends of the catastrophic flow channels. The surface is consistent with the stripping anticipated by a Roche-limit encounter. The low-density Martian moons appear to be unconsolidated material of higher density; they appear to be from low-gravity aggregation of that part of the Martian debris that went into orbit as a short-lived ring. A Roche-limit encounter is invoked as a reasonable hypothesis to explain these features. Earth, Mars' nearest planetary neighbor, may have ...