Wilson effect
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Wilson effect
(wil -sŏn) The apparent displacement of the umbra of a sunspot relative to the penumbra as the spot is carried by the Sun's rotation from the east to the west limb of the disk. For a symmetrical sunspot, the side of the penumbra closest to the center of the disk is more foreshortened than that toward the limb. This was first interpreted as implying that the spot is a depression, but it is now known that the opacity of the umbra is less than that of the penumbra and that this also contributes to the effect.Collins Dictionary of Astronomy © Market House Books Ltd, 2006
Wilson effect
[′wil·sən i‚fekt] (astronomy)
An effect in which the penumbra of a sunspot appears narrower in the direction toward the sun's center than in the direction toward the sun's limb.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive
But at the time the Danny
Wilson effect hadn't yet been fully felt.
Accepted solar models currently account for the visual depression of sunspots, or "
Wilson effect", using optical depth arguments (e.g [36, p.
This is the so-called
Wilson effect, named for the 18th-century Scottish astronomer Alexander Wilson, who first called attention to the phenomenon.
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