Glossary term: Doppler Effect
Description: The Doppler effect is the change in detected wavelength (or frequency) of sound or light waves caused by the relative motion of the source toward or away from the observer. This effect allows astronomers to study the motion of any body (stars, galaxies, gas, etc.) that emits waves (e.g. electromagnetic radiation). For example, in the case of radiation emitted from a star with spectral lines at specific wavelengths, the wavelengths of all the spectral lines will be shifted. For speeds significantly less than the speed of light, the Doppler shift in frequency (or wavelength) is proportional to the relative velocity of the source in the line of sight of the observer divided by the speed of light.
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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".
