Glossary term: Extinction
Description: The reduction in intensity of starlight reaching us is called extinction. This reduction is due to absorption and scattering of light by particles along the path of light. Extinction could be due to Earth's atmosphere (called atmospheric extinction), material in the immediate vicinity of a star (called circumstellar extinction), or due to material between stars in deep space (called interstellar extinction). The atmospheric extinction is mainly due to aerosols and molecules present in Earth's atmosphere such as water, carbon dioxide, and ozone at optical and near-infrared wavelengths. Interstellar extinction is attributed to interstellar matter made up of gas and submicron-sized dust particles. Interstellar dust has a drastic effect on starlight as compared to the gas particles. Extinction is generally higher at shorter wavelengths and vice-versa making astronomical objects appear redder than their true color (reddening).
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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".
