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Evening Mercury

July 18, 2011

An extra point of light scoots low across the western horizon over the next few evenings: the planet Mercury. It pops into view about 30 or 40 minutes after sunset. It's quite bright, but it's also quite low in the sky, so it's tough to see through the lingering twilight. And any buildings or trees along the horizon will block it from view.

For the most part, Mercury would be an unpleasant place to visit.

Because Mercury is the closest planet to the Sun, each point on its dayside receives an average of about seven times as much energy from the Sun as the same-sized point on Earth. So daytime temperatures soar to more than 700 degrees Fahrenheit, with nighttime temperatures dropping to about 300 degrees below zero. And Mercury is also zapped by more ultraviolet and X-ray energy from the Sun, so visitors would need a lot of protection.

About the only pleasant spots on Mercury are its poles. They receive relatively little energy from the Sun, so they get lower doses of ultraviolet and X-rays, and temperatures stay cold. In fact, there's strong evidence of ice at the poles. It's inside deep craters, where sunlight never reaches the bottom. A spacecraft that's orbiting Mercury is trying to confirm that the ice is really there, and find out how much of it there is.

Explorers might be able to quarry the ice and use it for drinking water, oxygen, and rocket fuel -- helping to carve a comfortable life on an uncomfortable world.


Script by Damond Benningfield, Copyright 2011


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