blink comparator

noun

: an optical instrument by means of which two pictures identical in all but a few details (such as two images of the sky taken on successive nights) may be registered in a single visual field and viewed alternately in rapid succession

Tombaugh then used a blink comparator, a device that compares two plates and highlights moving objects. One moving speck turned out to be Pluto.

—Nancy L. Hendrickson, Astronomy, November 1998

Word History

First Known Use

1921, in the meaning defined above

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