What is the term for a comet’s bright tail?

The term for a comet’s bright tail is indeed "coma," but it's important to clarify the terminology related to comets to enhance understanding.

When a comet approaches the Sun, it experiences increased solar radiation and solar wind, which causes the ice and dust within it to vaporize and release gas and particles. This event forms a glowing envelope around the nucleus, known as the coma. While the coma is the gaseous outer layer that surrounds the nucleus of the comet, the tail of the comet is not specifically termed 'coma'. Instead, a comet can have both an ion tail and a dust tail, which are different components of its tail.

The ion tail, often referred to in the context of comet tails, is formed by charged particles that are pushed away from the comet by the solar wind and magnetic forces. The dust tail, on the other hand, consists of larger particles that trail behind the comet as it travels through space.

Thus, understanding that while "coma" refers to the glowing cloud of gas around the nucleus, the actual bright tail of the comet consists of both an ion and a dust tail, allows for clarity in terms of cometary structure and the phenomena observed during their orbits.