Which part of a comet is the only one that exists when the comet is far from the Sun?

Question

Quizplus · Accepted Answer

When a comet is far from the Sun, it is too cold for the icy materials to vaporize, and the solar wind is too weak to blow away any gas or dust. Therefore, only the solid nucleus, which is made up of rock, dust, and ice, exists at this point. The coma and tails only form when the comet gets closer to the Sun and the Sun's radiation heats up the surface of the nucleus, causing it to release gas and dust.

Which Part of a Comet Is the Only One That