2020 May 21

Phases of Venus
Image Credit & Copyright:
Richard Addis

Explanation: Just as the Moon goes through phases, Venus’ visible sunlit hemisphere waxes and wanes. This composite of backyard telescopic images illustrates the steady changes for Venus during its current stint as our evening star, as the inner planet grows larger but narrows to a thin crescent. Images from bottom to top were taken during 2020 on dates February 27, March 20, April 14, April 24, May 8, and May 14. Gliding along its interior orbit between Earth and Sun, Venus grows larger during that period because it is approaching planet Earth. Its crescent narrows, though, as Venus swings closer to our line-of-sight to the Sun. Closest to the Earth-Sun line but passing about 1/2 degree north of the Sun on June 3, Venus will reach a (non-judgmental) inferior conjunction. Soon after, Venus will shine clearly above the eastern horizon in predawn skies as planet Earth’s morning star. After sunset tonight look for Venus above the western horizon and you can also spot elusive innermost planet Mercury.

Tomorrow’s picture: South Carina

Richard Addis

说明: 就像月亮的位相会有变化一样,金星可见的日耀区也会有盈亏。这幅后院望远镜组合影像,呈现金星在目前以昏星之姿出现的期间,日耀区变宽但面积缩成蛾眉的景象。这幅影像中的金星从下到上,分别摄于2020年2月27日、3月20日、4月14日、4月24日、5月8日和5月14日。在地球与太阳之间的内轨道绕行的金星,在这段期间之所以会变大,是因为它越来越靠近地球。而它会窄如蛾眉,则是因为金星越来越接近地球与太阳的连线。将在6月3日最接近地球-太阳连线,但从比太阳高半度的位置切过的金星,它在此时的位置称为下合。接着不久之后,金星将出现在清晨的天空中,成为地球的晨星。在今晚的日落后,西方地平线上空可见到金星,同时也能找到行踪隐密的水星。

明日的图片: South Carina

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