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Moon and More Companions

October 8, 2015

The Curiosity rover has been slogging around inside a large a Martian crater for more than three years now. And one of its key findings is that the crater has gone through several periods when it was quite wet. In fact, there could even be patches of dampness today.

Gale Crater is almost a hundred miles wide and about three miles deep. It formed more than three-and-a-half billion years ago, when a giant asteroid slammed into the Martian surface.

Curiosity’s observations show that shortly after that, the crater filled with water. And the water appears to have stuck around for a million years or more — suggesting that the entire planet maintained a warm, wet environment for a long time.

The rover has found evidence of other periods of watery activity inside the crater. And just a few months ago, scientists reported evidence that damp spots could form even today.

The soil inside the crater contains a compound known as perchlorate. It attracts water from the atmosphere, and it acts as an antifreeze, keeping it liquid. So overnight, when the humidity is high, salty water could dampen patches of ground — adding to the “watery” history of Gale Crater.

And Mars is in especially good view right now. Tomorrow, it stands close to the left of the crescent Moon at first light. The planet looks like a modest orange star. The much brighter planet Jupiter is below Mars and the Moon, with the even brighter planet Venus above them.


Script by Damond Benningfield, Copyright 2015

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