What Are Days And Nights Like On The Moon? | HowStuffWorks

If we define a "day" as the amount of time it takes the sun to return to the same point on the moon's horizon after the moon completes a new revolution around Earth, then every lunar day lasts for 29.5 Earth days. This means that — on every orbit — the moon gets a little over two weeks' worth of daylight followed by an equal amount of nighttime. In other words, almost any given spot on the moon sees two weeks of continuous daylight followed by two weeks of continuous darkness.

An interesting exception can be found near the poles. Earth is tilted 23.5 degrees on its axis, but the moon has a less dramatic axial tilt of just 1.6 degrees. Ergo, the satellite's axis is almost perpendicular to the path taken by solar light as it travels from our sun to the moon. Close to the lunar poles, there are some deep craters whose bottoms haven't seen any sunlight in more than 2 billion years. They are quite literally "where the sun don't shine."

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Without an atmosphere to retain heat, lunar temperatures fluctuate like crazy during the moon's daylight-to-nighttime transition. The moon's surface can be as hot as 260 degrees Fahrenheit (127 degrees Celsius) while it's being illuminated by solar light. But when the surface goes dark, the temperature may plummet all the way down to -280 degrees Fahrenheit (-173 degrees Celsius).

Fortunately, no astronaut has ever had to suffer through these lunar temperature extremes. NASA's Apollo missions put Neil Armstrong and 11 other people on the moon from 1969 to 1972. All of these brave explorers landed there just after lunar dawn, when the moon was lit, but the surface temperature had yet to reach its sweltering, midday apex. Timing is everything on astronaut adventures.

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