Reply to : Bill Gray

>> It will wander slowly around in the expected circle, complete a loop,

start out for the next loop... then keep going until, by +30340, the
polar axis lies in the plane of the ecliptic, sort of the way that of
Uranus does today. Seasonal variations become extreme as large chunks of
the world have continuous sunlight in summer and continuous night in
winter. Run the animation backward, and you learn that our distant
ancestors faced similar problems. Yet another reason I tell people not to
trust Guide very much more than a few millennia from the present. The
standard IAU precession method wasn't really intended to handle this sort
of thing. <<

Given the above, and on a different, but related, matter, how certain can
we be that, as has been stated, the next opposition of Mars will be the
closest for 100,000 years ?

Ricbard.


E-mail from: Richard Mallett, 31-Oct-2002