I see Steve Allen has already supplied a thorough answer. Interested individuals might also scrounge through the list archives (http:// rom.usno.navy.mil/archives/leapsecs.html) since the topic has come up before. In fact, Demetrios Matsakis speculated on solar system wide timescales even before this list was started. My own skepticism over more extreme flights of fancy is expressed under "Future Directions" in http://iraf.noao.edu/~seaman/leap.
On Jan 11, 2006, at 7:01 AM, Daniel R. Tobias wrote:
If, however, this Martian second is actually defined as a particular multiple of the SI second, then the use of leap seconds on Mars would ultimately be necessary to account for any future changes in the length of the Martian day.
That is indeed the issue. Is there anybody from the geophysics side who can comment on long term trends in Martian length of day? I don't have an envelope large enough, but there are various issues to consider. The Hurtling Moons of Barsoom are much smaller than our own and should have a negligible tidal breaking effect. (See http:// www.freemars.org/mars/marssys.html, for instance, for their interesting history.) And do the Earth's oceans mediate our Moon's breaking or is that a crustal phenomenon? (The Earth-Moon system should better be regarded as a double planet, than planet and satellite.) On the other hand, Mars passes much closer to Jupiter, the 800 pound gorilla of the solar system, but then it is further from King Kong - the Sun, that is - and tides are an inverse cube effect. But Mars is much smaller and has a smaller moment of inertia in the first place - but then Mars is much smaller and the "lever arm" to grapple with it is less pronounced. Taken all together, one suspects that LOD(Mars) is many orders of magnitude more constant than LOD(Earth). One would not be flabbergasted to be utterly wrong, however. Hopeful news for John Carter fans: http://filmforce.ign.com/articles/679/679046p1.html Rob