Explanation:
Dark, smooth regions that cover the Moon's
familiar face
are called by Latin names for oceans and seas.
The naming convention is
historical,
though it may
seem a little ironic to denizens of the space age
who recognize the Moon as a
mostly dry and airless world,
and the smooth, dark areas as
lava-flooded impact basins.
For example, this elegant lunar vista, a
careful mosaic of telescopic images, looks
across the expanse of the
northwestern Mare Imbrium,
or Sea of Rains, into the
Sinus Iridum - the Bay of Rainbows.
Ringed by the Jura Mountains (montes), the bay is about
250 kilometers across, bounded at the bottom of the rugged
arc by Cape
(promontorium) Laplace.
The cape's sunlit face towers
nearly 3,000 meters above the bay's surface.
At the top of the arc is Cape Heraclides,
at times seen as a moon maiden.
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