In January $2025,$ the comet C$/2024$ G$3$ passed by the Sun at a close distance of $0\mathrm{.}09$ AU$.$ Because the comet was shining exceptionally bright, it is now called the Great Comet of $2025,$ and it is one of five comets in the last $100$ years that can be observed with the naked eye during daylight. Other less bright comets pass by the Sun frequently and they are observable through telescopes. Describe the materials of which a comet consist and explain why the bright tail forms.