Describe the parts of a comet.
the frozen part of the comet
the atmosphere of gases and dust
formed when the nucleus vaporizes
tail made of ions that appears to
point away from the comet’s orbit
tail made of small, solid dust particles

The different parts of a comet are nucleus, coma, ion tail and dust tail. Nucleus is the frozen part of the comet. Coma is the atmosphere of dust and gases formed when the nucleus vaporizes. Ion tail is the tail made of ions that appear to point away from the comet's orbit. Tail made up of small solid dust particles is the dust tail.

Explanation:

Comets are small and irregularly shaped bodies found in the space. They are mostly made up of a mixture of dust, water ice, carbon and silicon based compounds. The distinct parts of a comet are the nucleus, coma, ion tail and dust tail.

The solid frozen core of the comet is called the nucleus. It is made up of rock, dust, ice, a variety of organic compounds and frozen gases like carbon monoxide, methane, ammonia etc. When a comet comes close to the Sun, the solar radiation causes the volatile materials inside the core of the comet to vaporize and results in the streaming out of gases and dust from the nucleus.

This stream of dust and gas form a huge atmosphere around the comet's nucleus and is known as coma, which is about a million kilometer in diameter. The solar wind and the force exerted on the coma by the sun's radiation pressure interacts with the ingredients in the coma and cause a tail to form, which extends from the comet and points away from the Sun.

The two comet tails formed are dust and gas ion tails. The yellow colored tail made of small, solid dust particles is known as the dust tail. When the sunlight gently push these small particles away from the comet's nucleus, they form a diffuse, curved dust tail.

A blue colored gas ion tail is formed when the solar radiation ionizes the gas atoms in the coma and produce ions, which is then carried away from the sun by the solar wind. This tail is straighter and narrower and may extend millions of kilometers into space.

Only when a comet comes near the sun, the coma and tails appears. The tail and the coma disappears when it moves away from the sun, and the matter inside its nucleus freezes back into a rock-like material.

he forelimbs below belong to four species that descended in a direct line from the ancestral mammal shown above. of the four descendants shown, which species most likely appeared earliest in evolutionary history?