Glossary term: Brightness

Description: Brightness is the everyday term for the amount of light an object emits, or the amount of light we receive from an object. For historical reasons, astronomers describe the brightness of an object using the so-called magnitude system which is a logarithmic system – from an object of brightness 1, we receive about 2.5 times more than from an object of brightness 2, which is about 2.5 times more than from an object of brightness 3, and so on. Astronomers call the intrinsic brightness of an object the luminosity, defined as the energy the object emits in the form of radiation per unit of time. Changes in brightness can allow us to reconstruct physical processes, e.g. when a star grows and becomes brighter, or a darker object passes in front of a brighter one.

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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".