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Fig. 8.24
Isolated mare domes in various regions of the Moon, examined for comparison.
(
a
) Highland domes Gruithuisen
γ
(G1),
δ
(G2), and NW (G3). (
b
) Mare dome Yerkes 1 near crater
Yerkes in Mare Crisium. (
c
) Mare domes Vendelinus 1 and 2 near the western rim of Vendelinus.
Image credit: J. Phillips. (
d
) Mare dome Kies
π
(K1). (e) Mare dome Herodotus
ω
(He1). (
f
) Valen-
tine dome V1 and its northern neighbour V2. Image credit: K.C. Pau
Fig. 8.25
(
a
) Image of the crater Petavius under moderately high solar illumination, showing two
dark pyroclastic deposits located at its southern and its northern rim, respectively. (
b
) Image of
Petavius, showing the dome associated with the southern pyroclastic deposit (marked by
white
lines
). Image credit: P. Lazzarotti. In both images, north is
to the top
and west
to the left
of the dome and the length
l
of its shadow were measured in pixels. The correspond-
ing image scale in kilometres per pixel was obtained by measuring the diameters of
craters of known size in the field of view. The possible effect of sloping terrain
has to be carefully considered, as the measured shadow length is longer for down-
ward slopes and shorter for upward slopes, compared to horizontal terrain. A further
problem arising especially for low domes is that even under strongly oblique illumi-
nation the shadow does not begin at the dome summit but at some point on its flank,
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