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

Here are the parts of the comet:
1. NUCLEUS: This is the frozen part of the comet. It is also known as the core. It is made up of ice and dust which are completely covered by organic matter. The nucleus usually consist of frozen water but other materials that are in frozen forms can be found in it. Comet nuclei are usually less than 16 kilometer in diameter.
2. COMA: The atmosphere of dust and gases formed when the nucleus vaporize. The coma refers to the envelope of gases that surround the comet's nucleus. The coma plus the nucleus forms the head of the comet. The coma is about a million kilometer in diameter and is made up of gases and dust which sublime from the comet's nucleus.
3. ION TAIL: Tail made of ions that appear to point away from the comet's orbit. The charged solar particles convert the gases found in the comet to ions thus forming an ion tail.  The ion tail can measure over 100 million kilometer long and it accelerate much faster than the dust tail.
4. DUST TAIL: Tail made up of small solid dust particles. It is formed by radiation from the sun, which forces dust particles away from the coma. It usually point away from the sun because the tail are shaped by the solar wind. As the distance from the sun increases, the dust tail usually become faint and diminished.