Thursday , June 24 2021

Lunar Explorer Spies Movement of Shadows Near the South Pole of the Moon

At the North and South Poles of the Moon, the Sun is never 1.5 ° above or below the horizon. The resulting daylight and shadows are unlike anywhere else on the Moon or Earth. After zooming in to a small lunar plateau area near the South Pole, this visualization recreates the lighting conditions there over a period of two months, equal to two months on Earth.

When you get this close to the pole, the sun does not rise and set. Instead, as the Moon rotates around its axis, the Sun glides over the horizon, making a complete 360-degree journey across the terrain. Mountains up to 75 miles (120 kilometers) away cast a shadow over the landscape. With the sun at such a low angle, it never reaches the bottoms of some deep craters. Places where the sun never reaches are known as permanently shaded regions. They are locations of some of the coldest spots in the solar system and as such, they trap volatile chemicals, including water ice, which immediately sublimates (turning directly from a solid to a gas) in harsh, stuffy sunlight. It falls on most of the other parts of the moon.

The sun also seems to move in a circle at the poles of the Earth, but it also travels at a range of heights. For example, from the spring equinox to the summer solstice, the Sun climbs higher in the sky and reaches a height of 23.4 °. Only a few days around the equinoxes embrace the horizon. At the poles of the moon, the sun always Close to the horizon and shadows are consistently long, sweeping the surface with changing sun azimuth.

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