Copyright:Tunç Tezel (TWAN)
Text:
Keighley Rockcliffe
(NASA
GSFC,
UMBC CSST,
CRESST II)
中文翻譯:
你有沒有聽過土星（Saturn）和海王星（Neptune）在夜空中跳舞呢？當土星和海王星進入逆行（retrograde）時，它們看起來像是往後走了一樣！這是因為我們的地球在太陽周圍的運行速度比這兩顆外行星快。想像一下，整個太陽系就像一條運動場的跑道，地球在內側快速奔跑，當地球「追上」這些行星時，從我們的角度看，它們就會變得像是往後移動了！最近的幾個月裡，土星從雙魚座（Pisces）走到水瓶座（Aquarius）又回到雙魚座，而海王星則一直待在雙魚座，這是自1989年以來，土星和海王星在空中最接近的一次！
原文:
What does it mean for Saturn and Neptune to be in retrograde? Featured is a composite of images taken over 34 nights from May 2025 to February 2026 tracing Saturn (brighter, foreground) and Neptune (dimmer, background). Over that time, the two planets exhibited retrograde motion, meaning they appeared to move backward in the sky. This apparent backwards motion occurs when Earth overtakes the slower outer planets as they orbit the Sun. Imagine the Solar System is a running track. Earth “runs” faster along the inside of the track compared to the outer planets. As Earth approaches, aligns, and then “laps” the outer planets, they change position from ahead to behind from the Earth’s perspective. This perspective shift is what causes the outer planets to change position in the night sky. An animation corresponding to today’s image shows Saturn and Neptune’s months-long dance across the northern night sky. Saturn stepped from the Pisces constellation into Aquarius and back again while Neptune remained in Pisces. This is the closest Saturn and Neptune have been in the sky since their last conjunction in 1989.
來源:NASA每日圖片
