Jun 25 1998
From The Space Library
James L. Elliot, an astronomer at the Massachusetts Institute of Technology, and his colleagues, together with Lowell Observatory and Williams College, published findings in the journal Nature based on data obtained from NASA's HST. The data indicated that Neptune's largest moon, Triton, had warmed up significantly since the Voyager spacecraft's visit in 1989. Triton's temperature had risen from 37 K (-393°F or -236°C) to 39 K (-389°F or -234°C), a 5 percent increase. The astronomers traced the warming trend to seasonal changes in Triton's polar ice caps attributed to "an extreme southern summer," a cyclical phenomenon occurring every few hundred years. Other possible explanations included a changing frost pattern on Triton's surface, which could have caused the surface to absorb more of the Sun's warmth; or changes in the reflectivity of Triton's ice, which could have caused it to absorb more heat. Because of the warming, Triton's frozen nitrogen surface was turning into gas, making its thin atmosphere denser. The scientists hoped their study of the changes on Triton would provide insight into global warming on Earth, which has a more complicated environment than Triton. HST's "detection of an increase in the moon's atmospheric pressure," measured with one of the space telescope's three fine guidance sensors, had provided the clue to the increased surface temperature.
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