War of the Worlds

From: Rob Seaman <seaman_at_noao.edu>
Date: Wed, 11 Jan 2006 09:28:30 -0700

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:


Received on Wed Jan 11 2006 - 08:29:10 PST

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