Babinet point
From Glossary of Meteorology
One of the three commonly detectable points of zero polarization of skylight, neutral points, lying along the vertical circle through the sun; the other two are the Arago point and Brewster point.
The Babinet point typically lies only 15° to 20° above the sun, and hence is difficult to observe because of solar glare.The existence of this neutral point was discovered by Babinet in 1840.
