Glossary term: Night

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Description: Night is a period of darkness when the Sun is below the horizon. Night lasts from sunset to sunrise. On most of the Earth each 24 hour day has one night. However north of the Arctic Circle and south of the Antarctic Circle there are periods of darkness around the winter solstice where the polar night can last for months. Conversely these ares have no night around the summer solstice. The period when the Sun is just below the horizon is called twilight. During twilight, the Sun still illuminates part of the sky. Twilight is divided into three equal periods, civil twilight (when the Sun is zero to six degrees below the horizon), nautical twilight (Sun six to twelve degrees below the horizon) and astronomical twilight (Sun twelve to eighteen degrees below the horizon). Most astronomical observations are made at night.

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Term and definition status: This term and its definition is still awaiting approval

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".