color index
Americannoun
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the difference between the apparent photographic magnitude and the apparent visual magnitude of a star.
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the difference between the magnitudes of a star in any two spectral regions.
Etymology
Origin of color index
First recorded in 1920–25
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Why use a color index if it ultimately implies temperature?
From Textbooks ● Oct. 13, 2016
The color index and how the eye and film “see” colors are discussed.
From Textbooks ● Oct. 13, 2016
A color index of a star is the difference in the magnitudes measured at any two wavelengths and is one way that astronomers measure and express the temperature of stars.
From Textbooks ● Oct. 13, 2016
A color index might lead reporters with an appetite for eye-catching headlines to produce misleading stories of an out-of-control border.
From Washington Times ● Apr. 22, 2016
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
