THE SOLAR SYSTEM
The Caloris Basin.
This composite mosaic was
compiled from Mariner 10
images which have different
resolution limits, so that the
degree of detail is not the
same everywhere. The floor
of the basin, with its central
fractures and its outer region
of sinuous ridges, is well
shown. There are many
small craters on the outer
eastern floor; the large crater
in the extreme north-east
corner of the image is Van
Eyck, 235 km (156 miles)
in diameter. The Basin is
1500 km (over 900 miles)
in diameter, and is bounded
by a ring of smooth
mountain blocks rising
1 to 2 km (0.6 to 1.2 miles)
above the surrounding
surface. Unfortunately
only part of it was recorded
from Mariner 10; at each
encounter the same regions
were available. About
80 per cent of 10–20 km
(6–12 mile) Mercurian craters
are terraced; on the Moon
only 12 per cent of craters
in the same class are.C Atl of Univ Phil'03stp 2/4/03 2:57 pm Page 67