We always get thrilled whenever we hear something about our universe with all its vast and complex structures. Though it's difficult to digest all the facts and specifics about the mysterious universe, the study of it can show us our origin, present life and our future. Among others the one that attracted me most was comets, more specifically Halley's Comet. While other celestial bodies like sun, moon and star mostly appear and move in a predictable path, the comets are bit unpredictable. So man always has some chilling thoughts about comets. In ancient times comets were considered as god's messengers. Whenever they find a comet they occasionally take it as a good fortune like the birth of a king, otherwise it was taken as a bad omen of disaster. People at that time blamed comets for events like the eruption of the volcano Vesuvius, an outbreak of the black plague, a major fire in New York City and for a massacre of 280 people in Africa.
People came to know more about the comets after British astronomer Edmund Halley predicted the orbit of the Halley's Comet. To describe his theory Halley used Isaac Newton's theories on the motion of bodies and gravity and forecasted the course of the comet he observed in 1682. As per his calculation the comet that appeared in 1531, 1607 and 1682, would reappear in 1758. Halley died after 16 years of his prediction that is before he sees the final result of his forecast. And the comet appeared on a Christmas night in 1758, as per his prophecy. From that incident onwards the comet is known by his name as Halley's Comet and it visits earth once in 76 years.
How Halley came to the conclusion that this particular comet will be visible on the earth once in 76 years? Halley saw that celestial object's speed increases as it would go closer to the solar system and would slow down when it move away from the center. Moreover a comet would spend major part of its time at the edge of the solar system, rather than in the center of the system. With this observation he explained comets visibility and invisibility on the earth. On the basis of this observation Halley stated that the comet he had seen was the same one that had been observed in 1531 and 1607. By calculating the comet's next appearance on the earth he said that the same comet would return in 1758 and his prediction was absolutely right.
Halley's Comet's recent visit to earth was in 1986 and its average revolution period around the sun is 76 years. Though the next visit will be based on so many other phenomenon's still if we calculate its revisiting year, it shows that the comet's next visit to earth will be in 2061. Halley's scientific explanations for comets behavior and its visit to earth subsided people's fear for certain extent. But other concerns that arose in the middle were what will happen if a comet collides with earth? Whether comets passing other celestial bodies can lead to earthquakes or any natural catastrophes like that? Scientists were behind this for many years and finally in 1910 some astronomers were able to give accurate predictions on the path of the comets and its rear possibility of hitting the planet.
During Halley's Comet's last visit in 1986 a spacecraft called Giotto took close photographs of the comet. As per the photographs the comet has a very small rocky nucleus of nearly 8 by 15 kilometers and contains millions of miles of gas. Several spacecrafts from Russia, Japan and Europe went to space to make a gather with Halley's Comet in 1986. Though those spacecrafts collected some details, still studies are going on this regard. I collected information related to comets and Halley's Comet from my home PC connected to Verizon FiOS Internet. I am eagerly waiting for its next arrival with hope and prayers.