We all know that solar system's formation started from billions of years ago. Today we have a solar system with sun in the center and nine planets, some asteroids and some comets revolving around it. Among different celestial bodies its comets that we are going to discuss in this article.
For years people believed that comets would bring misfortune in their life. Historical records states that ancient people considered the appearance of comets as a sign of wars and plagues. So they were afraid of these extraterrestrial bodies as it appears in the sky in an unpredictable and unannounced manner. While they were able to predict the path of the sun and other planets, it was difficult for them to find the path of comets. That can be the main reason behind their fear of comets. Whatever it is as the days passed they came to know that comets are nothing but lumps of ice and dust that gravitationally interact with the sun. This information cleared their fear on comets.
Some of the famous comets we come across are Hale-Bopp, Swift-tuttle, Hyakutake, Halley's comet and shoemaker levy-9. Among these the most discussed one was Halley's Comet. People came to know more about this comet after British astronomer Edmund Halley forecasted the orbit of the Halley's Comet. Based on Isaac Newton's theories on the motion of bodies and gravity, Edmund Halley predicted that Halley's Comet will visit earth in 1758. And his prediction was absolutely right. The generally accepted fact is that Halley's Comet takes nearly 76 years to revolve around the sun and on the basis of this it is expected to reappear on the earth in 2061. Halley's scientific explanations on comets behavior helped to keep away peoples fear on comets appearance to some extent.
Hale-Bopp is the other comet that was seen towards the out part of the Jupiter's orbit. It was Alan Hale of New Mexico and Thomas Bopp of Arizona who first watched that unusually large and bright comet using their Hubble Space Telescope. Hale-Bopp holds the record for the longest period of visibility with our naked eyes that is more or less 19 months. Astronomers predicted that the comet will not appear for next two thousand four hundred years.
It was American astronomers who first viewed the Swift-tuttle comet in 1862. This comet moves closer to the sun every 120 years, and whenever it comes closer to the centre it will leave dust debris and this can be seen as a firework display in the sky. According to scientists, this comet has a chance to collide with earth when these two orbits come close to each other. For the time being this drastic incident won't happen as the comet will be keeping a safe distance from the earth on its next trip towards the centre of the solar system.
It's really interesting to watch planets movements and the different shapes the stars take on different seasons in a planetarium. But just like we protect our house with home alarms from companies like ADT Home Security System from extruders, we cannot protect or prevent our environment from disasters happening in the outer space. But so far we are safe, as most of the comets are keeping a safe distance from the sun and this will continue for some years. Even if some comets like sun-grazers get close to the sun they will break up and evaporate without giving any harm to our mother earth.
Comets are mostly referred as dirty snowballs as they are the remnants of the solar system. It is constituted of water, carbon dioxide, ammonia, and methane ices, other than dust. It will have a small frozen part called the nucleus, which contains icy chunks, frozen gases, bits of embedded rock and dust. Whatever the size and constituents of a comet we can get important information related to the origin of the solar system and the mysteries behind other planets from a comet.