Comets

What are Comets?

Comets are cosmic snowballs of frozen gasses, rock and dust and similar to the size of a small town. When a comet's orbit is approaching close to the sun, it heats up and releases dust and gasses into a giant glowing head. The dust and gasses form a tail that stretches away from the sun for millions of kilometres.


Source: http://solarsystem.nasa.gov/planets/profile.cfm?Object=Comets


Halley's Comet

This very famous comet was founded by English astronomer, Edmond Halley, who first calculated it's orbit in 1705. Halley's commet makes a full orbit around the sun every 75 to 76 years. It is the only visible short term that is clearly visible to the naked eye from Earth, which accounts to its many sightings.


Source: http://science.nationalgeographic.com/science/space/solar-system/asteroids-comets-article/

2013 Year of the Comets ISON , Lemmon , PANSTARRS (HD)
Big image
Big image

Why Comets are so Interesting?

Comet nuclei could range from 100 meters to being more then 40 kilometer across! Comets have been described to be "dirty snowballs", but really they have a dry, dusty, and rocky surfaces, suggesting that the ices are hidden beneath a crust. The most visible part of a comet is called the coma. Streams of dust and gas form a huge, extremely tenuous atmosphere around the comet called a coma plus the force pushed on by the sun's radiation pressure and solar wind creates a colosal tail to form, which points away from the sun. The coma and the tail become visible are illuminated by the sun and might become visible when it passes through the inner solar system. Molecules in the coma and tail excite some fo the molecules so they glow and form a bluish tail called the ion tail. Comets are remnants form the cold, outer regions of the vast solar system. They are thought to originate from two places, the Oort Cloud and the Kuiper Belt. Both of these are areas where materials left over from the formation of our Solar System that have condensed into icy objects. Both regions extend beyond the orbits of Neptune and Pluto but are still much closer then the first star. In ancient time, before scientist studied what comets actually are, people thought comets were a curse or harbinger of tragedy and misfortune.



Sources:

http://www.universetoday.com/40778/interesting-facts-about-comets/

http://solarsystem.nasa.gov/deepimpact/educ/CometFacts.html