RISING MOON

Look into darkness!

DURING YOUR FIRST LOOK at the Moon through a telescope, chances are it was painted chockablock in fantastic craters all along the day-night terminator line, like it is this first week of December. The striking 3D effect is thanks to the shadows cast by mountain ranges, hills, scarps, ridges, and crater rims.

Specifically on the 1st, the Apennine mountain range arcs north of the equator, not quite cradling the perfectly circular Eratosthenes, whose ragged rim projects spiky shadows onto its smooth lava-filled floor and central peak, and even longer spikes into the darkness to the west. You can see where artists of science-fiction stories were inspired to paint fantastic landscapes. But centuries before, Galileo knew that under a low Sun angle, even the gentlest of hills throw pointy shadows.

A solitary Mons Piton sprouts above the wrinkled sea of Mare Imbrium. The large elliptical Plato to the north is startling — watch how its shadows shrink in the next couple of hours.

Over the course of the next few nights, the Sun gradually illuminates Mare Imbrium. No one realized that it was an enormous impact basin until we got our first orbital view of Mare Orientale. Then the isolated mountains of Piton and neighboring Pico suddenly fit the picture; they are simply the tallest peaks of an entire ring, most of which is submerged under the lava that welled up from below long after the basin was first formed.

Jump halfway from the equator to the south pole to find the Straight Wall painting a black scratch across the surface. Return on the 30th to watch its shadow slowly break away from the terminator as the Moon rotates gracefully toward the Sun. By the next night, the scarp casts but a thin black line.