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More Moon and Planets

November 2, 2016

Compared to Earth, the Moon is bone dry. There are no lakes, rivers, or puddles anywhere to be found. Even so, there is some water on the Moon. Patches of ice hide inside dark craters at the lunar poles, and bits of ice are mixed with the powdery lunar dirt. And there’s even water mixed in with the mantle — the layer of rock below the Moon’s crust.

A recent study says that most of the water below the surface probably was delivered by rocky asteroids when the Moon was young.

Among other things, the study team compared the chemistry of the water found in moonrocks picked up by Apollo astronauts to the water on Earth and in asteroids and comets. More than 80 percent of the lunar water matches that found in a particular type of asteroid.

The study says these asteroids pounded the Moon from shortly after it formed until it was a couple of hundred million years old. Much of the lunar surface was covered with molten rock at the time. The water in the asteroids mixed with the magma, and was trapped when the Moon began forming a solid crust atop the mantle.

In the billions of years since then, impacts by other asteroids have gouged out deep craters. That blasted some of the trapped water onto the surface — revealing the history of lunar water.

Look for the Moon low in the southwest as darkness falls tonight. Venus, the “evening star,” stands to its lower left, with fainter Saturn close below the Moon.

Tomorrow: giving a “spark” to the universe.

Script by Damond Benningfield

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