Astronomy is a fascinating science because it deals with the mysterious phenomena that occur outside our planet. Scientists have uncovered and explained relatively few discoveries regarding the universe. There are unknown worlds out there that astronomers are trying to unravel. It is important to note that we have not yet found specific and accurate explanations that brought the existence of celestial objects as we know today. Among these are comets known by its rare appearance in coming close to Earth. Its long tail has been the fascination of sky watchers for thousands of years. Many have believed that the coming of comets predicts disasters such as drought, storms, and earthquakes. However, science has proven such beliefs to be a myth.
Compared to other cosmic bodies, the nature of comets is not thoroughly known. It is believed to be composed mainly of gases, dust, ice, and space debris. Scientists have never been able to put space probes on the surface of comets. While the scientific community has been able to take close-up views of comets, samples of foreign materials are yet to be taken from these celestial objects. Studying these amazing long-tailed objects is presently done from a distance by the use of telescopes only when it draws near to our solar system. Due to the different materials that make up a comet, astronomers have compared the mixture like a "dirty snowball". It is believed that its center called the nucleus or core is solid and most likely made up of rocks. As the object travels through space, its icy surface melts to form its magnificent tail which is a trailing plume of ice vapor and debris. Its length can reach millions of kilometers.
How comets originate is one fact that cannot be thoroughly explained by science. Scientists have come up with theories regarding the birth of comets. One theory explains that they began to exist millions of years ago from gases that were left after the formation of the sun and the solar system. A gaseous mist called the Oort cloud became denser as the space debris cooled down. Due to the strong gravitational attraction of the sun and the planets, this large mass of ice and rock broke down into smaller fragments and causing comets to form. However, it is not exactly known why these objects visit the solar system in a period of time and why they have peculiar orbits.
The scientific community also believed that comets have different life expectancies and these are classified based on the length of their existence. Since these objects are made up of ice and debris, these are expected to melt down or burn out over a span of time. Long-period comets are those that exist for more than two centuries while short-period ones have a life expectancy of less than that time. This is a relatively shorter existence compared to the sun, planets, and stars that can be expected to last for millions of years.
For centuries, people have seen but have never had any close encounters with these foreign objects. It was only at recent times when scientists were able to study comets using sophisticated devices. An American space probe was able to gather information of material composition from the tail of the comet Giacobini-Zinner in the year 1985. The following year, scientists around the world collaborated in launching a probe that made a pass near Haley's Comet. There will be more in-depth research in the future when comets come close to the Earth's orbit.
As far as catastrophe is concerned, the possibility of a collision of comets and the Earth is unlikely. Astronomers have studied the orbits of comets and have found out that a said course is very rare. Chances of this disaster is very slim compared to the potential hazards caused by asteroids. Due to this fact, we can gaze comfortable at the night sky and appreciate the spectacular display of comets even once in our lifetime.
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