Glossary term: Earth

Description: Earth is the third planet of the Solar System and one of its inner planets, together with Mercury, Venus, and Mars. It is the fifth largest planet in the Solar System in terms of diameter and mass, and has the highest density. Earth is home to millions of species of living creatures, including humans; it is the only place to date known to have life in the Universe. It is believed to have formed about 4.54 billion years ago. Earth has an atmosphere that works to block harmful radiation and hence allowed the multiplication of organisms that live only in the presence of oxygen and the formation of the ozone layer. Earth also has extensive surface water (the only planet in the solar system known to do so), giving it a blue color.

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The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".

Related Media

The Earth from space showing oceans and continents

Earth as observed from Apollo 17

Caption: Full disk view of the Earth taken on 7 December 1972, by the crew of the Apollo 17 spacecraft en route to the Moon at a distance of about 29,000 kilometres (18,000 mi). It shows Africa, Antarctica, and the Arabian Peninsula.
Credit: NASA/Apollo 17 crew/Project Apollo Archive
License: PD Public Domain icons