Comets - Comets
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Q: what do you know about Comets ?
| Option | Answer | Is Correct |
|---|---|---|
| 1 | Comets are small solar system bodies, usually only a few kilometers across, composed largely of volatile ices. They have highly eccentric orbits, generally a perihelion within the orbits of the inner planets and an aphelion far beyond Pluto. When a comet enters the inner Solar System, its proximity to the Sun causes its icy surface to sublimate and ionize, creating a coma: a long tail of gas and dust often visible to the naked eye. Short-period comets have orbits lasting less than two hundred years. Long-period comets have orbits lasting thousands of years. Short-period comets, such as Halley’s Comet, are believed to originate in the Kuiper belt, while long period comets, such as Hale-Bopp, are believed to originate in the Oort Cloud. Many comet groups, such as the Kreutz Sungrazers, formed from the breakup of a single parent.Some comets with hyperbolic orbits may originate outside the Solar System, but determining their precise orbits is difficult. Old comets that have had most of their volatiles driven out by solar warming are often categorized as asteroids. |
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