地球所有的水

2022年9月26日

All the Water on Planet Earth
Illustration Credit: Jack Cook, Adam Nieman, Woods Hole Oceanographic Institution; Data source: Igor Shiklomanov

Explanation: 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.

Tomorrow’s picture: DARTing an asteroid

地球所有的水
图示提供与版权: Jack Cook, Adam Nieman, Woods Hole Oceanographic Institution; 数据来源: Igor Shiklomanov

说明: 地球有多少成分是水？其实非常的少。虽然海水覆盖了70%的地球表面，但相对于地球半径来说海洋非常浅。这张主题图示指出，如果把地球表面和附近所有的水聚集成球，球体的半径大约只有700公里，不到月亮半径之半，但是略大于土卫五；而类似太阳系外围的大部分卫星，土卫五的主要成分是水冰。此外，第二小的那颗球代表地球所有液态水的存量，而最小的球呈现所有淡水湖和河流的总量。然而，如此大量的水为何会出现在地球上，地表之下是否藏有大量的水，仍然是科学研究的课题。

明日的图片: DARTing an asteroid