Description: This term refers to the phenomenon where the wavelength of electromagnetic radiation is shifted to shorter wavelengths. The word blue in blueshift is historical, as blue is situated in the short wavelength region of the visible spectrum. The shift in wavelength is the result of relative motion between the observer and the source that is emitting electromagnetic radiation. Blueshift is the electromagnetic radiation version of the Doppler effect of sound waves. It is important to note that shift (blueshift or redshift) in the wavelength of electromagnetic radiation is detected by measuring the shift in spectral lines of objects compared to spectral lines of elements at rest in a laboratory. Blueshift (and redshift) is not related to the visible colors of stars we can observe in the night sky.

Related Terms:

• Doppler Effect
• Electromagnetic Radiation
• Wavelength
• Redshift

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".