NASA每日一图 ·

美国国家航空航天局NASA每日一图(天文)-2017年8月11日(一个全日食的Saros 145  )

2017 August 11

A Total Solar Eclipse of Saros 145 
Image Credit & Copyright: Tunç Tezel (TWAN), Alkim Ün
Explanation: A darkened sky holds bright planet Venus, the New Moon in silhouette, and the shimmering corona of the Sun in this image of a total solar eclipse. A composite of simultaneous telephoto and wide angle frames it was taken in the path of totality 18 years ago, August 11, 1999, near Kastamonu, Turkey. That particular solar eclipse is a member of Saros 145. Known historically from observations of the Moon's orbit, the Saros cycle predicts when the Sun, Earth, and Moon will return to the same geometry for a solar (or lunar) eclipse. The Saros has a period of 18 years, 11 and 1/3 days. Eclipses separated by one Saros period belong to the same numbered Saros series and are very similar. But the path of totality for consecutive solar eclipses in the same Saros shifts across the Earth because the planet rotates for an additional 8 hours during the cycle's fractional day. So the next solar eclipse of Saros 145 will also be a total eclipse, and the narrow path of totality will track coast to coast across the United States on August 21, 2017.

2017年8月11日

一个全日食的Saros 145 
图像信用和 版权: TunçTezel (TWAN), AlkimÜn
说明: 一个黑暗的天空持有明亮的行星金星,新月的轮廓,以及太阳的闪烁的 电晕 在这个全日食的形象中。同时长焦和广角镜架的复合材料是在一九九九年八月十一日,土耳其卡斯塔莫努附近的整个路线中采取的 。这个特别的日食是Saros 145的成员。 从历史上的月球轨道观测来看, Saros循环预测当太阳,地球和月球将在太阳(或月球)日食时返回相同的几何。萨罗斯有18年,11和1/3天的时间。由一个Saros时期分开的日食属于相同编号的Saros系列,非常相似。 但是,由于行星在周期的分数日内再转动8个小时,所以同一Saros中连续太阳日食的总体路径将跨越地球。所以下一次Saros 145的日食也将是一次全面的日食,而整个这个狭窄的路径将会在2017年8月21日在美国跟踪到海岸线 。

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