什么是消光现象

有些分子具有旋光性，分为左旋和右旋，相同摩尔的左右旋光混合就会失去旋光性，就是消光。

天文方面的吗？星际尘埃散射星光，使星光减弱，使肉眼就看不清楚了...
天体辐射从发出到被我们接收之前,被途中的气体和尘埃吸收和散射,使得辐射被削弱,称为消光.

In chemistry, absorption of light by a chemical substance is called extinction of light, and can be described by its "extinction coefficient".
A compound, or its molecules, generally has one (or more than one) absorption maximum at certain wavelength. The specific wavelength and the numeric order of extinction coefficient can be used to qualitatively identify a given type of compound.