from the sun's by > 90 degrees, the relation is where β is the ecliptic latitude and is smaller than 60°, when larger than 60 degrees the contribution is that given in the table. Along the ecliptic plane there are enhancements in the zodiacal light where it is much brighter near the sun and with a secondary maximum opposite the sun at 180 degrees longitude (the gegenschein). In extreme cases natural zenith sky brightness can be as high as ~21.0 mag/arcsec², roughly twice as bright as nominal conditions. See also Night sky Airglow Zodiacal light Light pollution Skyglow References Observational astronomy Atmospheric optical phenomena Plasma physics Space plasmas Earth phenomena Light pollution Sky