Comet

Definition

A comet is a small celestial body made of ice, dust, and rocky materials that orbits the Sun, often exhibiting a distinctive glowing coma and a tail when it approaches the inner solar system. These icy bodies originate from the outer regions of the solar system and are thought to be remnants from its early formation, providing insight into the primordial materials that contributed to planet formation.

5 Must Know Facts For Your Next Test

1. Comets are classified into two main types: short-period comets, which take less than 200 years to orbit the Sun, and long-period comets, which have orbits lasting thousands or even millions of years.
2. The coma of a comet can be several times larger than the Earth, formed by gases sublimating from the nucleus as it approaches the Sun.
3. When comets pass close to the Sun, they can release significant amounts of water vapor and organic molecules, making them important for understanding the chemical building blocks of life.
4. Comets have been observed throughout history, often seen as omens or celestial events, and some famous comets include Halley's Comet and Comet Hale-Bopp.
5. The study of comets helps scientists learn about the conditions in the early solar system, as they contain primitive materials that have remained largely unchanged since their formation.

Review Questions

• How do comets differ from asteroids in terms of composition and behavior in the solar system?
  • Comets primarily consist of ice, dust, and rocky materials, while asteroids are mostly composed of metal and rock. When comets approach the Sun, their ices vaporize and form a glowing coma and tail due to solar radiation and wind, which is a behavior not seen in asteroids. Additionally, comets usually have highly elliptical orbits that take them far out into the solar system before returning close to the Sun, while asteroids tend to have more circular orbits in the asteroid belt between Mars and Jupiter.
• Discuss how studying comets contributes to our understanding of the early solar system and the origins of water on Earth.
  • Studying comets provides insights into the conditions present in the early solar system because they are made up of primordial materials that have remained largely unchanged. Comets can contain significant amounts of water ice and organic compounds, suggesting they may have contributed water and complex molecules to Earth during its formation. This connection helps scientists explore theories about how life may have originated on our planet and whether similar processes could exist elsewhere in the universe.
• Evaluate the role of comets in shaping our understanding of cosmic chemistry and the potential for life beyond Earth.
  • Comets play a crucial role in cosmic chemistry as they serve as time capsules containing organic molecules and other fundamental building blocks necessary for life. Their study reveals how these materials were distributed throughout the solar system and potentially seeded planets like Earth with essential components for life. By analyzing cometary compositions through missions like Rosetta and others, scientists can assess whether similar processes might occur on exoplanets or other celestial bodies, offering clues about life's potential existence beyond our own planet.

Related terms

Nucleus: The solid core of a comet, composed of ice and dust, which can range from a few hundred meters to tens of kilometers in diameter.

Oort Cloud: A hypothetical spherical shell surrounding the solar system, believed to be the source of long-period comets, extending from about 2,000 to 100,000 astronomical units from the Sun.

Tail: The visible part of a comet that forms as solar radiation and solar wind vaporize the nucleus's ices, creating a glowing cloud of gas and dust that is pushed away from the Sun.