美国国家航空航天局NASA每日一图(天文)-2017年7月28日

2017 July 28

Noodle Mosaic of Saturn
Image Credit: NASA, JPL-Caltech, Space Science Institute, Hampton University
Explanation: On April 26 the Cassini spacecraft swooped toward Saturn on the first of its Grand Finale dives between Saturn and rings. In this long, thin, noodle mosaic, a rapid series of 137 low resolution images captured by Cassini's wide-angle camera track its progress across the gas giant's swirling cloud tops. The mosaic projection maps the arc along Saturn's atmospheric curve on to a flat image plane. At top, the first mosaic panel is centered at 90 degrees north, about 72,400 kilometers above Saturn's dark north polar vortex. As the mosaic progresses it narrows, the pixel scale shrinking from 8.7 kilometers to 1 kilometer per pixel. For the last panel, the spacecraft is 8,374 kilometers above a region 18 degrees north of Saturn's equator. Frame orientation changes near the bottom as Cassini rotates to maneuver its large, dish-shaped, high-gain antenna forward, providing a shield before crossing Saturn's ring plane.

2017年7月28日

土星面条马赛克
图片来源: NASA, JPL-Caltech, 空间科学研究所, 汉普顿大学
说明: 4月26日,卡西尼号的飞船在土星和环之间的第一次大决赛潜水中向土星 射击。在这个 漫长而薄的面条马赛克中,卡西尼广角摄像机拍摄的137张低分辨率图像的快速系列追踪了其在气体巨头的旋转云顶上的进步。马赛克投影将电弧沿着土星的大气曲线映射 到平面图像平面。在顶部,第一个马赛克面板以北部90度为中心,距离土星的黑色北极涡旋约72,400公里 。随着马赛克进程的缩小,像素尺寸从8.7公里缩小到每像素1公里。对于最后一个面板,航天器是8, 距离土星赤道以北18度的地区374公里。随着卡西尼旋转,框架方向在底部附近变化,以便向前移动其大的碟形高增益天线, 在穿过土星的环形平面之前提供屏蔽。

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