Aspen in Space
| NANTES, FRANCE—For an extraterrestrial skiing experience, Enceladus is the place to go. Parts of this small, icy Saturnian moon are covered with a thick layer of extremely powdery snow, according to a presentation here today at a joint meeting of the European Planetary Science Congress and the Division for Planetary Sciences of the American Astronomical Society. Consisting of particles just a few micrometers in size (creating the halo in this artist's impression), the snow has been accumulating over millions or even tens of millions of years. Last year, scientists predicted that some of the material spewed out into space by the icy geysers at Enceladus's south pole would slowly fall down to certain areas on the surface. Detailed measurements by NASA's planetary probe Cassini, presented at the meeting, have now revealed the predicted snow fields, which measure up to 100 meters thick. They betray their presence by their conspicuous bluish color and by softening the outlines of buried craters and canyons (inset). But prospective skiers should take care not to launch themselves into space: the gravity on tiny Enceladus is just 1% that of Earth. | 法国南特消息—要想体验一下在地外的滑雪感受，就去土卫二上好了。今天，欧洲行星科学大会和美国天文学会行星科学部在这里举行的联合会议上提交的一篇报告中说：在土星这颗冰封的小型卫星上，部分区域覆盖着厚厚一层极细的粉末状积雪。积雪是在几百万年甚至几千万年的时间里积累起来的，由直径仅有几微米的微粒构成，在这张艺术家描绘的印象图中产生了光晕。去年，科学家们预测，土卫二南极的冰泉喷到太空中的一些物质还会缓慢地降落到表面上特定区域。NASA的“卡西尼”号行星探测器获得了详细的测量数据。目前，提交到会议上的数据揭示了预测的落雪地点，落雪厚度达100米。显眼的浅蓝色使被掩埋的陨石坑和峡谷的轮廓显得有些逊色（见插图），这样就暴露了这些落雪地点。但是，打算滑雪的人应该注意：不要轻易把自己发射到太空——在小小的土卫二上，引力只有地球的1%。 |
联系客服
