The distinct blue color of the nebulosity around stars in young clusters,such as the Pleiades,is caused by
A) light emitted by very hot gas which has been heated by collisions in the interstellar gas.
B) preferential scattering of blue starlight by small dust grains in the interstellar material.
C) atoms of gas emitting light by fluorescence,having been excited by ultraviolet radiation from hot stars.
D) halos caused by refraction of starlight in ice crystals in the nebula,similar to halos seen occasionally in Earth's atmosphere.

Question

Quizplus · Accepted Answer

The distinct blue color of the nebulosity is caused by preferential scattering of blue starlight by small dust grains in the interstellar material. This is known as Rayleigh scattering, which occurs when the size of the scattering particle is much smaller than the wavelength of the light being scattered. The blue light from the young stars in the cluster is scattered more efficiently than the other colors, giving the nebulosity a blue color.

The Distinct Blue Color of the Nebulosity Around Stars in Young