1. The disappearance of an extremely distant galaxy from a telescope image when viewed through an ultraviolet filter, caused by the absorption of the galaxy's emitted ultraviolet radiation by intergalactic hydrogen gas.
2. A technique that identifies galaxies as extremely distant by comparing images taken through visible light (in which distant objects are often detectable) and ultraviolet filters (in which they are not).
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.