Illustration Credit: Jack Cook, Adam Nieman, Woods Hole Oceanographic Institution; Data source: Igor Shiklomanov
How much of Earth is water? Surprisingly little. Oceans cover about 70% of the planet’s surface, but compared to Earth’s size, they are just a thin layer.
If all the water on or near Earth’s surface were gathered into a single sphere, it would only be about 700 kilometers across, less than half the size of the Moon, and a bit smaller than Saturn’s moon Rhea, which is mostly ice.
A much smaller sphere would represent all of Earth’s liquid fresh water, and the tiniest sphere would show just the water in rivers and lakes. Scientists are still studying how Earth got its water and how much more might be hidden deep underground.
source APOD
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