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Glossary term: Plasma

Description: Plasma is a hot ionic gas made up of an approximately equal number of positive ions and negative electrons. The properties of plasma are so different from those of ordinary neutral gases that plasma is considered a "fourth state of matter". Plasma can form at high temperatures (as in stars) or by photoionization (as in interstellar gas). Plasma is found in the interstellar medium, in the interplanetary medium in the form of the solar wind, and within the planetary magnetosphere. It is estimated that 99% of the matter in the observable Universe is in the plasma state. Hence the expression "plasma universe".

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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".