History of Comets and their Impact

Comets Throughout History

• Comets have fascinated humans for over 2,000 years, as evident from ancient records, paintings, and drawings on caves and cloths, as well as written observations.

Comets and Disasters

• Throughout history, comets have been blamed for disasters, calamities, and tragedies, such as earthquakes, illnesses, and bloodshed.
• The ancient Romans believed that a comet marked the assassination of Julius Caesar, and another comet caused extreme bloodshed during the battle between Pompey and Caesar.

Discovery of Comets

• Sir Edmond Halley is credited with the discovery that comets are part of the solar system.
• The name "comet" comes from the Greek word "kome," meaning "hair," referring to their long, wispy tails.

Characteristics of Comets

• Comets are usually discovered as faint, fuzzy patches of light on the sky, still several astronomical units away from the Sun.
• They travel in highly elliptical orbits with the Sun at one focus.
• As a comet approaches the Sun, its icy matter becomes heated, sublimes, and develops a tail.

Sublimation Process

• Sublimation is the process by which a solid changes directly into a gas without passing through the liquid phase.
• Frozen carbon dioxide (dry ice) is an example of a solid that undergoes sublimation.

Composition and Structure of Comets

• Comets are fragments of icy material that normally orbit far from the Sun.
• Unlike other bodies in the solar system, comets have highly elongated orbits that bring them into the inner solar system.
• A comet's nucleus or core is only a few kilometers in diameter, surrounded by a coma of dust and gas, and an extensive invisible hydrogen envelope.

Appearance of Comets

• As a comet approaches the Sun, its surface ice vaporizes, and we see the comet by the sunlight reflected from the dust and vapor released.
• A comet's tail is formed by the interaction between the cometary material and the solar wind, with the ion tail pointing directly away from the Sun, and the dust tail having a curved shape.

This quiz explores the fascinating history of comets and their effects on human societies, from ancient records to modern times. It delves into how comets have been perceived and blamed for disasters throughout history.