|Category: Science and Technology: Astronomy: Amateur Astronomy: Solar System Observing: Comets|
Comets are small heavenly bodies that orbit the Sun. They have a core center and may or may not have a tail. They orbit the Sun at very long intervals in highly elliptical orbits. They travel by the Earth on a circular schedule. Comets have been observed since ancient times and have traditionally been considered bad omens.
Comets have a cardinal nucleus called coma. Comet nuclei are known to range from about 100 meters to more than 40 kilometres across. This coma is composed of rock, dust and icing. As the comet gets nearer to the Sun, the ice melts and this produces a lot of dust and rubble. As the pressure of the sun increases, the solar wind pushes the debris and rubble into a beautiful comet tail. The sun lights up the tail and we can see the comet from world.
Comets have a wide range of orbital periods, ranging from a few years to hundreds of thousands of years. Short-period comets originate in the Kuiper belt, or its associated scattered disc, which lie beyond the orbit of Neptune. Longer-period comets are thought to originate in the Oort cloud, a hypothesized spherical cloud of icy bodies in the outer Solar System.
Before the invention of telescopes, comets would appear out of nowhere. It seemed like they would illuminate themselves all of a sudden, not contrary to the recent comets. Comet Holmes saw an outburst in just a few weeks that made it visible on Earth with the naked eye. Before, it had only been visible as a vague image in a telescope.
Now scientists are capable to see and discover comets that would otherwise not be visible on Earth. Because of the rotary nature of comets. Some comets may only appear every several century years. The number visible to the naked eye averages roughly one per year, though many of these are faint and unspectacular. There's always a chance for an amateur with a telescope to discover a never before seen comet, much like the discovery of the Hale-Bopp Comet in 1996.
Comets are believed to originate in the Oort Cloud. The Oort Cloud is located in the farthest reaches of our solar system and is nearly 3 light years in size. It is in the Oort Cloud that comets originate and return to. Since this huge distance and the huge size of the Oort Cloud, Comets come at regular intervals of hundreds of years. This is compounded by the highly elliptical orbits of Comets. For example, the most famous comet, Haley's Comet comes every 76 years. Unfortunately, it's the only naked eye viewable comet that comes so often. All known comets have their origin within the Solar System, rather than entering the system on a highly hyperbolic trajectory.
Comets are the source of folklore and beauty in our sky. A comet gives us a chance to really see the beauty in astronomy.