Cometary

Cometary refers to the characteristics, phenomena, and behaviors associated with comets. Comets are small Solar System bodies that, when passing close to the Sun, heat up and begin to outgas, displaying a visible atmosphere (or coma) and sometimes also a tail. These features are both temporary outgirdings of particles illuminated by the Sun. Cometary activity is primarily driven by the sublimation of volatile substances such as water ice, carbon dioxide, and ammonia.

Composition and Structure

Comets have a diverse range of compositions, primarily made up of water ice, dust, and rocky material, which has led them to be famously described as "dirty snowballs" by astronomer Fred Whipple. The structure of a comet generally consists of a nucleus, coma, and tail:

• The nucleus is the solid core of the comet, typically a few kilometers across.
• The coma is a cloud of water vapor, carbon dioxide, and other gases liberated from the nucleus.
• The tail is formed when the Sun's heat and solar wind pressure push dust and gases away from the coma, stretching out into space.

Dynamics and Behavior

The behavior of comets is highly dynamic and changes as they orbit the Sun. Their activity levels increase significantly when they come closer to the Sun due to increased solar radiation, which causes the sublimation of their icy components. This process leads to the jet-like ejection of material from the nucleus, causing the comet to sometimes develop spectacular tails.

Observation and Study

Cometary bodies are of great interest to astronomers and space scientists because they are believed to be pristine remnants from the formation of the Solar System. Studying them can provide valuable insights into the early solar nebula and the processes that led to the formation of planets.

Historical Impact

Throughout history, comets have been viewed with both awe and alarm, often considered as omens. Historical records of comets, such as Halley's Comet and the impact of Comet Shoemaker–Levy 9 with Jupiter, have provided important milestones in the study of cometary science.

See Also

• Asteroid
• Meteoroid
• Kuiper Belt
• Oort Cloud