Meteors, Asteroids and Comets - Term Paper Example

Meteors, Asteroids and Comets Describe the meteors/asteroids/comets that traverse our solar system. How many of them travel near to the Earth? Describe past collisions between these objects and the Earth and the effect that these collisions apparently have had on evolution. What can be done to protect the human race against future catastrophic collisions? Introduction The heavenly bodies that surround our planet include a lot more than the planets and the stars. While we know that most of space is nothing but vacuum the heavens are also filled with bits and pieces of matter which can be observed in the shape of meteors, asteroids and comets that occasionally may be seen with the naked eye (NASA, 2007). Of course there are significant differences between them just as there are differences between planets and stars but there is also a level of threat associated with them as they move around space. To understand these minor players in cosmic terms is important for any student of geology, history, astronomy, physics and even social sciences since they can have an impact on how we think about the solar system as well as the world around us. Therefore, it would be best if each of these players is examined individually before a discussion can be made about their possible impact on earth in the past and the future. Comets Comets are small bodies in the solar system that go around the Sun in a more or less elliptical orbit. They are distinguished by their tail which is created due to the partial atmosphere the comets have and due to solar radiation acting upon the comet. Some parts of the comet may include rock along with ice. Their elliptical orbit often brings them close to the sun and they can even strike planets in their path such as the comet that struck Jupiter a few years ago. When they move close to a planet, their movement as well as their orbit can be affected by the gravitational pull of the planet body that can cause them to crash into their sun or even move out of their set orbits (NASA, 2007). While in ancient times, comets were given a mythical status today we know and understand them far better. In fact, a dozen comets are discovered each year and we know that most of the comets come from a region of icy bodies which is located beyond the orbit of Neptune. The comets coming from this belt have relatively short orbits and more or less have predictable paths. On the other hand, comets coming from a distant region called the Oort cloud can take as long as 30 million years to complete one orbit therefore their path is rather difficult to calculate or estimate (NASA, 2007). Of course the distinctive tail or tails that a comet shows makes them one of the more wondrous objects in the night sky even if they can be rather difficult to trace or manage in terms of how they are travelling across the heavens. Asteroids Asteroids on the other hand, do not have a tail as such since they have no atmosphere with them. They are essentially the remnants of the creation of the solar system which took place nearly five billion years ago. The majority of the asteroids in the solar system are to be found in a belt between mars and Jupiter which is known as the Asteroid Belt or the Main Belt. These asteroids far outnumber other objects within the solar system since there are millions of these with sizes ranging from a small pebble to others which reach the size of dwarf planets (NASA, 2007). For example, Ceres is an asteroid which reaches almost a quarter of the size of the moon. Many asteroids have been identified, named or numbered and at present there are more than 90,000 known asteroids in the solar system. As asteroids revolve around the Sun in their orbits, gravity from giant planets such as Jupiter or a very close brush with a planet like Mars can alter their directional heading which takes them out of the main belt. In fact, it is theorized that the moons of Mars i.e. Phobos and Deimos could be former asteroids (NASA, 2007). Meteors These players in the solar system are commonly known as shooting stars and they are simply parts of matter which are pulled towards the earth and then heat up with the friction due to the atmosphere of the earth to harmlessly burn out. This bright streak of light that can be seen with the naked eye due to a meteor burning in the atmosphere is termed a meteoroid and if this streak is able to strike the ground it is called a meteorite. It is interesting to note that an estimated 1,000 tons to more than 10,000 tons of meteorites fall on to earth everyday to burn up in the atmosphere or to turn to dust and fall harmlessly to the ground beneath us (NASA, 2007). However, in some cases the impact is not at all gentle and could result in cataclysmic changes for the planet as well as all forms of life that inhabit the world (Powell, 2000). Scientists believe that stray asteroids or parts of an asteroid may have slammed into Earth in the past, and this played a major role both in changing the geological history of our planet and changed the path of the evolution of life (Benton, 2003). For example, the extinction and total decimation of dinosaurs as well as many other species of plant and animal life 65 million years ago has been linked to a meteorite impact that took place near the Yucatan peninsula in Mexico (NASA, 2007). Past Collisions Geographical evidence as well as the topographical map data of the earth shows us that there have been massive collisions of astronomical objects with the surface of the earth. In fact, there are quite a few locations on earth which could be pointed as the crash site of a giant meteor that landed on earth to cause an extinction level event that killed off all the dinosaurs and made way for mammals and in turn human beings to become the dominant species on earth. The protection offered by the atmosphere of the earth is quite useful in limiting the number of meteorites that reach the surface of the planet. However, impact events in the past have been caused by large comets or asteroids that have come close enough to the earth to be pulled in by gravity. The surface of the moon for example, is dotted with many different craters that show the impact of small and large bodies that can easily reach the surface of the moon due to a lack of a real atmosphere. Benton (2003) notes that extinction events in the past have caused many species to be wiped out. The largest such event is the Permian extinction which took place a quarter of a billion years ago where over 90% of all life forms on the planet were killed. The death of the dinosaurs is credited to an impact which took place 65 million years ago. The evidence for that is seen in the Yucatan peninsula which is a part of a crater that is almost a 100 miles in diameter. Such an impact would have created massive tsunamis across the oceans, disturb millions of tonnes of material into the atmosphere causing fires to rage across the world and it would have covered the world in darkness preventing photosynthesis for a long enough period of time to kill most plant species. In fact, there have been five noted impact events that resulted in the ends for different eras in geologic history. Each event caused life on the planet to take a new direction with the ouster of older species. Future Collisions Of course the logical question then becomes regarding the occurrence of the next collision. There are quite a few problems with making that prediction since there are a lot of objects which are flying about the heavens and their paths often come very close to the orbit of the earth. In recent times there have been well publicised cases of near misses and close calls where asteroids have crossed within a few thousand miles of earth and had they impacted earth the results could have been devastating. The US Congress is particularly aware of the situation and has asked NASA to monitor the situation for them. NASA has already discovered and located more than 80% of the largest NEOs (Near Earth Objects) and has plans underway to identify and plot the paths of 90% of all NEOs that are larger than 1 kilometre in size. These giants could have a devastating impact on our civilisation if they were to collide with the planet. At the same time, NASA is looking to mark all NEOs that are more than 140 meters in diameter to prevent a localised catastrophe if such objects were to strike any location on the planet (Shiga, 2006). Writing for Discover Magazine, Powell (2000) suggests that, “there is no question that a cosmic interloper will hit Earth, and we wont have to wait millions of years for it to happen (Powell, 2000, Pg. 1)”. He then lists smaller impact events that have happened in the past such as the Tunguska event in Russia that occurred in 1908 releasing more than a thousand times the energy of the atomic bomb that was used on Hiroshima. That impact was the result of an object only two hundred feet wide. The magnitude of the threat was defined by him as: “An asteroid five miles wide would cause major extinctions, like the one that may have marked the end of the age of dinosaurs. For a real chill, look to the Kuiper belt, a zone just beyond Neptune that contains roughly 100,000 ice-balls more than 50 miles in diameter. The Kuiper belt sends a steady rain of small comets earthward. If one of the big ones headed right for us, that would be it for pretty much all higher forms of life (Powell, 2000, Pg.1)”. Of course in all probability, the impact of an object is likely to be small and it is likely to be in water since the majority of the globe is covered with water. Even on land, the majority of the earth is covered by desolate regions with a few urban population centers forming the bulk of the population centers. However, since larger asteroids and comets are certainly out there in the cosmos, there is no reason why they could not strike us in the future. This strike could happen in a few years or in a few million years but it is very likely to happen. Survival? In such an event it is unlikely that too many humans would be able to survive the impact unless they are heavily protected with supplies of food and water that keeps their existence sustained until the planet has settled down and recovered from the impact of the floating outsider. Of course, once those humans come out of their shelters and protected habitats, they might find a new world for them which is very different from the one they had previously occupied. In conclusion, it seems that humans could survive such an impact if they knew about the even coming and had enough warning to prepare themselves and others in how to deal with the object heading towards earth. For example, attacks could be made on the object with nuclear powered missiles or other means could be used to make sure that the body could be averted from heading towards earth but until we have the technology or the know how to do that we are living under threat from our heavenly neighbors who may pay us an unexpected visit. There is some solace in the fact that even in the worst case scenarios, some humans are very likely to survive since our present level of civilization means that we have the technology to create reinforced bunkers and underground living quarters that could be used to house some seed population within them. However, once those humans come out they will find that they have lost all that can be considered a part of humanity since the present high level of civilization that put them there in the first place may no longer be there for them to come back to. The biggest support we have in our handling such events is information and that information comes from dedicated scientists and workers looking up at the heavens with the best tools that can be found to seek answers where even the questions can be difficult to understand. Works Cited Benton, M. 2003, When Life Nearly Died: The Greatest Mass Extinction of All Time, Thames and Hudson. NASA. 2007, ‘Our Solar System’, [Online] Available at: http://solarsystem.nasa.gov/planets/profile.cfm?Object=SolarSys&Display=Overview Powell, C. 2000, ‘Twenty ways the world could end suddenly’, [Online] Available at: http://findarticles.com/p/articles/mi_m1511/is_10_21/ai_65368918 Shiga, D. 2006, ‘New telescope will hunt dangerous asteroid’, [Online] Available at: http://space.newscientist.com/article.ns?id=dn9403&feedId=online-news_rss20 Word Count: 2,186 Read More