What fraction of Earth's surface is covered by ocean?
AnswerAbout 71%
Oceans cover roughly 71% of the planet's surface and hold about 97% of its water.
Science · Facts & stats
Earth facts & stats
7 fact-checked facts about how our planet works and how to keep it working, each with the reason behind it. 5 more are in today's round and join this page after it closes.
The basics
Which layer of Earth do we live on?
AnswerThe crust
The crust is the thin outer rock layer; the mantle and core lie beneath it.
Going deeper
Roughly how old is Earth?
AnswerAbout 4.5 billion years
Radiometric dating of meteorites and the oldest minerals puts Earth at about 4.54 billion years.
Which biome stores the most carbon in its soils?
AnswerPeatlands and wetlands
Peatlands cover ~3% of land but store about a third of soil carbon; draining them releases it.
Earth Day is held each year on which date?
AnswerApril 22
Earth Day began on April 22, 1970 and is now observed in more than 190 countries.
Expert level
What percentage of Earth's water is fresh and accessible at the surface (lakes, rivers, soil)?
AnswerLess than 1%
About 2.5% of water is fresh, and most of that is locked in ice and groundwater; surface fresh water is well under 1%.
Which event about 66 million years ago ended the age of non-avian dinosaurs?
AnswerAn asteroid impact at Chicxulub
The Chicxulub impact in present-day Mexico, with volcanic activity, drove the end-Cretaceous extinction.
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