Lunar Reconnaissance Orbiter Spies Movement of Shadows Near the Moon’s South Pool

At the Moon’s North and South Poles, the sun is never more than 1.5 ° above or below the horizon. The resulting pattern of daylight and shadows is different from anywhere else on the moon – or on earth. After zooming in on a small lunar highland near the South Pole, this visualization recreates the lighting conditions there over a period of two months, equivalent to two months on Earth.

That near the pole, the sun does not rise and set. As the moon rotates on its axis, the sun rather shifts through the horizon and moves 360 degrees around the terrain. Mountains up to 120 km away cast shadows over the landscape. When the sun is so low, it can never reach the floors of some deep craters. Places that never reach the sun are known as permanent shadow regions. These are the places of some of the coldest places in the solar system, and therefore they trap volatile chemicals, including water ice, which would immediately sublimate (directly from a solid to a gas) in the harsh, airless sunshine that falls on most other places on the moon.

The Sun also appears to move in a circle toward the Earth’s poles, but it also moves through a variety of heights. From the spring equinox to the summer solstice, for example, the sun rises higher in the sky and reaches an altitude of 23.4 °. It embraces the horizon just a few days around the equinoxes. At the moon’s poles is the sun always near the horizon, and the shadows are constantly long and sweep across the surface with the changing sonasimut.

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