Comets are large rocks that travel through space. Space is very cold, so comets are covered in ice and other frozen materials. When they move towards a sun, however, they are warmed and develope an impressive tail which you can see in a telescope. A comet's tail is made up of gas. Can you explain how this tail is formed? Be sure to name any changes of state which you think have occured.

Sure, let's break down the process step by step:

1. Comet Composition: Comets are composed of rock, dust, and various ices (such as water ice, carbon dioxide ice, methane ice, etc.).

2. Cold Environment: In the cold environment of space, these materials remain frozen.

3. Approaching the Sun: As a comet travels through space, it sometimes moves closer to a sun (or star).

4. Warming Up: When the comet approaches the sun, the increase in temperature causes the frozen materials on the comet's surface to warm up.

5. Sublimation: The heat from the sun causes the ice to change directly from a solid state to a gas state. This process is called sublimation.

6. Formation of the Coma: The gas produced from sublimation, along with dust particles, forms a glowing cloud around the nucleus of the comet. This cloud is called the coma.

7. Solar Wind and Radiation Pressure: The solar wind (a stream of charged particles emitted by the sun) and radiation pressure push the gas and dust away from the comet, forming a tail.

8. Tail Composition: The tail of the comet is primarily made up of gas and dust. The gas tail is formed from the sublimated gases, while the dust tail is composed of small solid particles.

9. Visibility: The tail becomes visible from Earth when observed through a telescope, as the sunlight reflects off the gas and dust particles.

In summary, the tail of a comet is formed when the comet approaches the sun, causing the ice to sublimate into gas. This gas, along with dust particles, is then pushed away by the solar wind and radiation pressure, creating the visible tail.