- Because comets appear suddenly and look different from other celestial bodies, some historical cultures fear them while others revere them.
- Comets were believed to foretell the death of kings, the demise of great empires and the creation of plagues.
- The appearance of Halley's comet in 1066 was believed to foretell the loss at the Battle of Hastings.
- In 1910, when spectroscopy was new to the world of science, toxic gases were found in Halley's comet. When Earth passed through the comet's tail, some people encouraged the sale of "comet insurance policies" and special medicines for "Comet Fever".
- There is the theory that comet impacts on Earth provided both the water and possibly the carbon-based molecules necessary for life.
- About 40,000 tons of dust particles from comets and asteroids fall to Earth every year.
- Comets are both a potential threat and a potential resource. Comets have hit Earth in the past. At some point in the future we will need to know how to draw from their resources and also to protect ourselves against their impacts.
- As the primitive, leftover building blocks of the outer solar system's formation process, comets offer deep within them, clues to the chemical mixture from which the giant planets formed about 4.5 billion years ago.
- See Comets in Ancient Cultures for more information.
But how do we find out more???