Explanation:

Tyndall Effect

As comets move close to the Sun, they develop tails of dust and ionized gas. Comets have two main tails, a dust tail and a plasma tail. The dust tail appears whitish-yellow because it is made up of tiny particles, about the size of particles of smoke that reflect sunlight. Tail of comets is seen as a Tyndall cone due to the scattering of light by the tiny solid particles left by the comet in its path.