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Mercury Rising

May 28, 2013

Mercury is the closest planet to the Sun, so it gets pretty hot — temperatures max out at more than 700 degrees Fahrenheit. Yet some parts of the planet stay ice cold — cold enough, in fact, to support thick slabs of water ice.

Planetary scientists have suspected there’s water on Mercury for decades. Radio telescopes here on Earth have found evidence of ice inside craters at the planet’s poles — spots that never see sunlight. And last year, the Mercury-orbiting Messenger spacecraft confirmed that suspicion.

Messenger’s instruments detected the “fingerprint” of water ice in some of those shadowy craters. The ice might be the remains of comets that slammed into the planet over the eons.

In some places, the ice may be more than 60 feet thick. And some of those ice beds are covered with a dark coating of organic molecules. The coatings may help protect the ice and keep it from vaporizing and escaping into space.

The Messenger readings suggest that Mercury could have up to a million million tons of frozen water — safely hidden away inside dark craters.

Mercury is in great view right now. The little planet is low in the west-northwest at sunset, above the brighter planets Venus and Jupiter. Mercury looks like a fairly bright star itself. Over the next few nights it will climb higher into the sky each evening. Unfortunately, it will fade as it does so. But it will remain fairly close to Venus, helping us find this “watery” world.


Script by Damond Benningfield, Copyright 2013

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