地球上所有的水
All the Water on Planet Earth
發表日期：2025-09-07
地球上有多少是由水構成的？其實很少。雖然海洋覆蓋了地球表面的 70 %，但與地球半徑相比，這些海洋都很淺。這幅插圖展示瞭如果把地球表面或附近的所有水都擠成一個球會發生什麼。這個球的半徑只有大約 700 公里，還不到地球月球半徑的一半，但比土星的衛星瑞亞稍大一些。下一個最小的球表示地球上所有的液態淡水，而最小的球表示地球上所有淡水湖泊和河流的體積。這些水是如何出現在地球上的，以及是否有大量的水被困在地球表面之下，仍然是研究的課題。
原文：How much of planet Earth is made of water? Very little, actually. Although oceans of water cover about 70 percent of Earth's surface, these oceans are shallow compared to the Earth's radius. The featured illustration shows what would happen if all of the water on or near the surface of the Earth were bunched up into a ball. The radius of this ball would be only about 700 kilometers, less than half the radius of the Earth's Moon, but slightly larger than Saturn's moon Rhea which, like many moons in our outer Solar System, is mostly water ice. The next smallest ball depicts all of Earth's liquid fresh water, while the tiniest ball shows the volume of all of Earth's fresh-water lakes and rivers. How any of this water came to be on the Earth and whether any significant amount is trapped far beneath Earth's surface remain topics of research.
※ 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。