“Life’s but a walking shadow, a poor player, that struts and frets his hour upon the stage and then is heard no more; it is a tale told by an idiot, full of sound and fury, signifying nothing.” –William Shakespeare
Ahh, the glorious shadows of our Universe. Everywhere that sunlight is blocked gives us shadow.
For the Earth, of course, this results in night and day each time the Earth rotates.
The Earth, though, is also tilted on its axis a significant amount, by about 23.5 degrees. When a pole tilts towards the Sun, it receives continuous daylight, while when it tilts away from the Sun, it resides in continuous shadow.
Over the course of a year, every place on the Earth’s surface receives light. And — when you couple that with the Earth’s relatively warm atmosphere — you’ll find that every place on the Earth’s surface receives some amount of heat, too.
But is that true everywhere?
Welcome to the Moon, as imaged back in the 1990s by Clementine. The Moon also orbits, revolving around the Earth (which in turn revolves around the Sun), but also rotating about its own axis.
But the Moon is quite unlike the Earth, which rotates with a tilt of 23.5 degrees.
The Moon is tilted at a meager 1.5 degrees with respect to the Sun. Which means that there are practically no seasons on the Moon; all places on the Moon receive roughly the same amount and type of sunlight at all times of the year.
as well as the far side,
as imaged by the Lunar Reconnaissance Orbiter (LRO). You’ll notice, of course, that the Moon is covered in craters.
Imagine the North and South poles of this Moon, if you will. If you lived there, you’d only ever receive glancing sunlight; the Sun would only ever appear to be 1.5 degrees above the horizon, at most. What does this mean for craters located at the poles?
We don’t really need to wonder. LRO has created mosaics of the North (left) and South (right) poles of the Moon, and you can see the very suggestively “permanently shadowed” craters!
These are interesting, because once anything falls into them, including remnants from meteors, nothing ever warms them! No sunlight, no heat, no atmosphere, they simply cool and freeze. One of the remarkable things that’s expected to be in these craters? Frozen water, a.k.a. ice!
So what do these poles actually look like, if you fly over them? Well, that’s as close to a “glimpse” of these deepest shadows that you’ll ever see. And LRO has a beautiful flyover of the North Pole to show you!