Glossary term: Earth
Description: Earth is the third planet from the Sun and is the fifth largest planet in the Solar System. It is a rocky, terrestrial planet with a radius of about 6400 kilometers (km). It has a mass of about six trillion, trillion kilograms.
The Earth's typical distance from the Sun is about 150 million kilometers. This is defined as one astronomical unit. The Earth takes 365.26 days to complete on orbit of the Sun. The Earth has one natural satellite known as the Moon.
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 and magnetosphere that work to block harmful radiation and hence allow the multiplication of living organisms. 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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Term and definition status: This term and its definition have been approved by a research astronomer and a teacher
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
Earth as observed from Apollo 17
Credit: NASA/Apollo 17 crew/Project Apollo Archive
License: PD Public Domain icons
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