Forthcoming 2007/2008 Mars
(17)
Watch
the
CMO #341 (10 January
2008)
Masatsugu
MINAMI
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T |
he movement
of the tilt of the south pole this apparition is quite different than that of
15 years ago. In 1992/1993, the tilt was always away from the Earth during the
early autumn, while this apparition it is toward us from 1 January (λ=011°Ls) to 29
February (λ=039°Ls). This
implies this season is favoured in the sense we can observe the south
circumpolar polar region at the season when the north polar cap remains large.
In 1992/1993, the south autumnal equinox visited on 21 Nov 1992 when
φ=12.9°N and then down but the tilt was
maximum with φ=3.8°N at λ=039°Ls. On
the contrary this year the southern tilt is toward to us until λ=039°Ls.
We are
now appreciating the hypothesis of W. H. PICKERING that the maximal polar caps
cannot exist at the same time. Some numerical experiments based on the pure CO2 atmosphere theory predict a growing of the
spc just before λ=025°Ls (while
maximum
is retarded until after λ=090°Ls,
winter solstice), but before that the spr will be obscured by the nph.
Unfortunately since DS gradually goes down to the north
(intersection point of the dotted lines in the Figure (due to NISHITA)), the
defect of illumination will affect near the area of the south
pole soon. Nevertheless this is the best chance for us to watch the
trend of the south circumpolar region in the southern early autumn. Any image
should be accompanied by B ingredient and processed carefully paying attention
to the southern terminator.
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