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Moon and Mars
It’s been clear for a while that Mars was much warmer and wetter in the distant past. Ancient riverbeds wind across its surface, and some of the minerals on the surface form only in a wet environment.
Some recent research suggests that the warm, wet days lasted longer than expected.
The Curiosity rover has been studying layers of rock at the base of a mountain inside a large crater. Their composition suggests they formed as pebbles and sand settled on the bottom of a lake that filled the crater.
The layers of sediment could be anywhere from a few hundred feet to half a mile thick. Thinner layers would have been deposited over millions of years. But it could have taken tens of millions of years to deposit thicker layers. Based on the age of the crater, that means it could have been filled with water as little as 3.3 billion years ago — much more recently than suggested by studies of the Martian climate.
Another study examined a salt flat near the Curiosity landing site with spacecraft in Mars orbit. The salt bed probably formed from sediments at the bottom of a lake or sea. The feature is no more than 3.6 billion years old — suggesting that this region of Mars was one of the last “wet spots” on the planet.
And look for Mars quite close to the Moon in the wee hours of tomorrow morning. It rises below the Moon, and looks like a bright orange star. The planet Saturn is below both of them, and we’ll have more about that tomorrow.
Script by Damond Benningfield