西月東海

Western Moon, Eastern Sea

來源：The Mare Orientale｜發表日期：2026-07-10

“東方海”（拉丁語：Mare Orientale）是月球上最引人注目的大型地貌之一。作為月球上最年輕的大型撞擊盆地，從地球上幾乎無法觀測到它。不過， 7 月 7 日恰逢月球近地側傾角（即月球近地側的擺動）處於有利位置，在這張清晰的望遠鏡拍攝影像中，仍可在右上角發現東方海。在這張影像中，這片巨大的月海因透視效應而顯得極其短縮，沿月球西緣延伸。該撞擊盆地形成於 30 多億年前一顆小行星的撞擊，直徑近 1000 公里，其同心圓形的特徵是月殼中的漣漪。但在從月球軌道拍攝的該區域更直接的影像中，這些特徵則更容易辨認。那麼，為什麼“東海”位於月球西緣呢？“東海”（Mare Orientale）這一月球地貌的命名早於 1961 年。正是從那一年起，月球地圖上標註東西方向的慣例發生了逆轉。

原文：The Mare Orientale, Latin for Eastern Sea, is one of the most striking large scale lunar features. The youngest of the large lunar impact basins it's very difficult to see from an earthbound perspective. Still, captured on July 7 during a period of favorable tilt, or libration of the lunar nearside, the Eastern Sea can be found at the upper right in this sharp telescopic view. In the image, the large lunar mare is extremely foreshortened and stretches along the Moon's western edge. Formed by the impact of an asteroid over 3 billion years ago and nearly 1000 kilometers across, the impact basin's concentric circular features are ripples in the lunar crust. But they are a little easier to spot in more direct images of the region taken from lunar orbit. So why is the Eastern Sea at the Moon's western edge? The Mare Orientale lunar feature was named before 1961. That's when the convention labeling east and west on lunar maps was reversed.

※ 本文由萌芽機器人自動轉貼自每日一天文圖（Astronomy Picture of the Day，APOD），原文為英文，正體中文是透過 DeepL 翻譯及 OpenCC 進行自動處理，內容僅供參考，若有任何錯誤之處還請見諒！

關於每日一天文圖：每日一天文圖網站是美國國家航空暨太空總署與密西根理工大學提供的服務，網站每天提供一張影像或圖片，並由天文學家撰寫扼要說明其特別之處。