精选美国宇航局图片（1）

tjhx0526 2015-04-08

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【美景】精选美国宇航局图片（1）

照片是在火星拍的，呵呵！！

星云！

　国际空间站

Scientists who study dust storms have long known that Saharan dust can travel across the Atlantic to the Americas. Asian dust, however, must travel much farther to reach the same destination. In April 2001, researchers watched with surprise as dust from an Asian storm crossed the Pacific reaching as far east as the Great Lakes and even Maryland.
　　
　　An eye-witness to the dust storm, who visited Jilin Province in northeastern China, reported that around 7 a.m. local time on April 7, 2001, the dust blocked enough sunlight to leave the skies as dark as midnight, and reduced visibility to roughly 20 meters (65 feet). The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured these images of the dust storm as it swirled over China the same day.
　　
　　An April 2001 temperate cyclone spun counter-clockwise over China, pushing a wall of dust as it moved. The deep tan dust is not only thick enough to completely hide much of the land surface below, but it almost forms its own topography, with ridges of dust rising up below the clouds.
　　
　　A U.S. Navy Aerosol Analysis and Prediction System (NAAPS) model predicted where it would travel, which relies in part on data from NASA/s Sea-viewing Wide Field-of-view Sensor (SeaWiFS) sensor.
　　
　　A 2005 paper by Jianguo Liu and Jared Diamond described the increased incidence of dust storms in China. From AD 300 to 1949, China experienced a dust storm on average every 31 years. After 1990, a dust storm occurred almost every year. The authors attributed the increase in such storms partly to deforestation and changes in water usage.

不好意思小弟英文学的不好，有些自己也看不懂什么意思，不过我会把英文介绍尽量一起发上来！6
　　Resembling the fury of a raging sea, this image actually shows a bubbly ocean of glowing hydrogen gas and small amounts of other elements such as oxygen and sulfur.
　　
　　The photograph, taken by NASA's Hubble Space Telescope, captures a small region within M17, a hotbed of star formation. M17, also known as the Omega or Swan Nebula, is located about 5,500 light-years away in the constellation Sagittarius. The image was released to commemorate the thirteenth anniversary of Hubble's launch.
　　
　　The wave-like patterns of gas have been sculpted and illuminated by a torrent of ultraviolet radiation from young, massive stars, which lie outside the picture to the upper left. The glow of these patterns accentuates the three-dimensional structure of the gases. The ultraviolet radiation is carving and heating the surfaces of cold hydrogen gas clouds. The warmed surfaces glow orange and red. The intense heat and pressure cause some material to stream away from those surfaces, creating the glowing veil of even hotter greenish gas that masks background structures. The pressure on the tips of the waves may trigger new star formation within them.