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- THE WEEK, Page 23HEALTH & SCIENCEFire and Ice
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- Frozen water has been found on the searing surface of Mercury
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- The planet Mercury is truly a hellish place: it is one-third
- as far from the sun as Earth, and its daytime temperatures can
- reach 430 degreesC (800 degreesF). The last thing scientists
- expected to find there was ice. But that is just what a new
- radar study of Mercury, reported in Science, has detected.
- Planetary scientists at NASA's Jet Propulsion Lab and at Caltech
- aimed powerful radar beams at both of the planet's poles; the
- return signals bore the telltale signs of having bounced off a
- frozen surface. Like Earth and Mars, Mercury appears to have
- polar ice caps.
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- How is it possible? An analysis by UCLA scientists points
- out that while the poles are bathed in scorching sunlight, the
- light hits at such a shallow angle that the floors of some
- craters are permanently in shadow. With no atmosphere to move
- heat around, the temperature in these spots is far below zero.
- Any ice that condensed as frost in the craters billions of years
- ago when water boiled on the planet's surface as it formed would
- still be around today -- and evidently is.
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