Near Earth Objects - Research Paper Example

? In school we hear all sorts of things about asteroids, meteors, and comets. We stay up late to watch meteor showers, and use powerful telescopes toobserve everything in the sky and beyond. While there are plenty of things to observe in deep space, there are also a number of objects that can be found close to the Earth. Some of these objects actually do enter the Earth’s atmosphere. At specific times of the year, meteor showers can be observed, their fiery tails sweeping across the night sky for all to see. Another type of Near Earth Object that can be seen is the comet. Depending on how close they are to the Earth, they can be spotted with the naked eye, or they can be spotted with a telescope. Rather than clustered together, a comet is a single large object with a long tail. More often than not, it is the tail, and not the main part of the comet that can be seen. Near Earth Objects might be fun to look at, but they are capable of doing catastrophic damage. Craters around the world pay homage to the respect that they undoubtedly deserve. One of the most widely accepted theories for the extinction of dinosaurs is that a massive meteor struck the planet and radically changed both climate and atmosphere. Fortunately, when it comes to this modern age, there are methods and theories in which to deflect NEOs. All of these are untested, however, and have only performed in labs. A meteor, or meteorite, is a body of rock, ice, or metal that enters the Earth’s atmosphere. Many of these are small and harmless, and burn up upon entering the atmosphere. When you see a shooting star, or a meteor shower, that is what you are seeing. While no threatening meteors have recently struck the Earth’s surface, the evidence is all around us. The largest crater in the world, created by a meteor, is in South Africa in an area called the Vredforte Dome. This meteor hit the Earth more than 2 billion years ago, and was around 10 km in diameter. According to science, the impact of the meteor might have been massive enough to jumpstart multicellular life by increasing the amount of oxygen in the atmosphere. There are, to date, 841 World Heritage sites around the world. A World Heritage site is a special place that has either a cultural or a physical significance. These sites are chosen by the UNESCO (United Nations Educational, Scientific, and Cultural Organization), which has been around since 1945. While Earth appears safe for the most part, it has had its share of close calls. One such close call occurred in September of 2004. An asteroid by the name of Toutatis swept by Earth, missing it by about a mile. Several kilometers in diameter, if Toutatis or a rock like it were to hit Earth, it would devastate life as humans know it. The sun would be obscured by a huge cloud of dust that would travel around the globe, changing the temperature and climate of the Earth. Plants would start to die from lack of sunlight, unable to complete their cycles of photosynthesis, and herbivores would begin to starve. Humans would have major crop failure as well, and would need to resort to another means of sustenance. Eventually, over time, civilization would cease to be. Food, if any survived at all, would be both precious and hard to come by. Water would become stagnant and toxic to drink, as the evaporation process would be altered without sunlight. The impact of a NEO of this size would ultimately either destroy all life on the planet, or force evolution into overdrive. A rare NEO that is usually only seen by astronomers with high-powered telescopes and other special equipment is the comet. These massive objects are made up of ice and organic material. They carry behind them a long ‘tail’, which consists of ice and other materials that it picks up as it hurtles through space. The ‘head’ of the comet is called a nucleus, which consists of the ice and organic materials. The core of the nucleus is as yet unknown. These beautiful objects are far older than many of the planets in the solar system, the majority of them estimated to be 4.6 billion years old. There is the possibility that comets that crashed into the surface of the Earth brought water and other organic life forms to this planet, helping to kick start life. There are three types of comets: Jupiter family, sungrazing comets, and long-period comets. Jupiter family comets take only around 20 years to orbit around the sun. They are believed to have come from the Kuiper Belt, which is situated near Pluto in the outer solar system. Up to one trillion rock-ice bodies are known to be in this ‘belt’. Sungrazing comets are the reckless risk takers of the comet families. They travel dangerously close to the sun, some within a mere 50,000 km. That may seem like an incredibly long distance away, but the gravitational pull of the sun is such that it may pull sungrazing comets right into it. The last type of comet is the long-period comet. These typically take 200 years or more to orbit around the sun. Some of them, however, can take upwards of one million years to travel around the sun. For a long time no one really knew where long-term comets came from, but the Oort cloud carried the answers. Housing an untold number of comet nuclei, this cloud rests on the outer limits of the sun’s gravitational power, and is named after Jan Oort. The speed in which a comet can travel can vary, and is generally between 2-40 km/second. The closer to the sun a comet is, the faster it will move in order to keep from getting pulled into the massive sun. When a comet is furthest from the sun, it will slow down considerably. Some comets that have come close enough for people on Earth to see have been Hyakutake (1996), Hale-Bopp (1997), Halley’s Comet (1742), Comet Swift Tuttle (1992). Another incredibly famous comet is called Comet Shoemaker –Levy 9. This comet collided with Jupiter in 1994, and made history. It was the very first time anyone had witnessed a collision between a comet and a planet. This only brings to light even more that the possibility for a collision between Earth and a comet is entirely possible. When Comet Shoemaker-Levy 9 hit Jupiter, massive plumes kilometers high stretched out into space like fiery fingers. An asteroid is another creature again. It is easy to confuse a meteor and an asteroid, but there is an easy way to eliminate this confusion: a meteor, or meteorite, enters the Earth’s atmosphere, and an asteroid does not. However, an asteroid, a comet, or pieces of either can enter the atmosphere of the Earth and become meteors. The largest known asteroid is almost 1000 km in diameter, and is called 1 Ceres. 2 Pallas, 4 Vesta, and 10 Hygiea are next on the list, but are also impressive. All three are between 400 and 500 km in diameter. While those four large asteroids already mentioned are not currently dangerous to Earth, there is one that is. It is 320 meters across, and was discovered in 2004. It stoked something of a stir in the astronomy community when it was realized that this particular PHA would find its way in or very near Earth’s orbit. Astronomers, at the time, estimated that there was a chance it would hit in 2029… that’s 25 years later. Further research concluded that Apophis would probably miss Earth, and the chance that it would hit went from 1-37 to 1-48,000. Toutatis, at a few km across, wracked worldwide devastation. What would happen, however, if an asteroid 500km across or more entered the Earth’s atmosphere? Even with today’s technology, there is still no sure way to move it off its course if it was discovered 25 or more years in advance. This asteroid would be moving at around 20km/second (750,000 km/hr), and deliver every ounce of energy upon impact because of the sudden stop. There is no doubt that an object of this size would strike deep within the Earth’s core, creating a massive 400,000 km crater that would be visible from space. Like Jupiter, the impact would hurl debris and other such things many kilometers into space, much of which would return to Earth as fireballs. From heat alone, the oceans would evaporate, and the world would become engulfed in a worldwide, unstoppable firestorm of flame and radiation. Nothing and no one would survive, and the heat from the initial blast would be equal to that of the sun (4000-6000 C). The immense accumulation of dust would block out the sun, and within a day the Earth would be no more than a super heated planet of rock and molten fire. Perhaps a year later, maybe more, the Earth would cool enough for the rains to come. As it did billions of years ago, the planet and life upon its surface would begin again. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts is widely responsible for discovering NEOs that could potentially become harmful to the planet. These are called PHA’s (Potentially Hazardous Asteroids), and must come within 7.5 million km of Earth to be considered such. In order to be truly hazardous, the PHA must exceed a diameter of 50m. They discover new ones almost every day, of various shapes, sizes, and materials. Another organization that does this type of work is the B612 Foundation. The B612 Foundation has an important goal in mind: using gravity to adjust the course of an asteroid. The asteroid they are intending to use for their first ‘experiment’ is a harmless one, not close to hurting the Earth should it enter the atmosphere. In order to use gravity to adjust the position of this NEO, they want to move a spacecraft beside it, and see if its gravitational pull will have enough influence to make the asteroid move. They, and many of the other organizations dedicated to watching NEOs, are against exploding threatening or non-threatening NEOs. There is no telling how the explosion will affect the movement of the object. Gravitational pull could draw all the pieces back together as well, creating a whole object again. There is too much risk, and not enough research to even consider something like that. Furthermore, a nuclear weapon would have to be employed in order to do the job, which raises further reaction questions. Another very large issue regarding the manual movement of NEOs is time. To date, asteroids that have hit the Earth have been detected far too late, meaning there wouldn’t be enough time to adjust their course to avoid the planet. If a very large NEO were detected even a week before impact, all anyone would be able to do would be to evacuate the area and hope for the best. Even if a very large ( 500+ foot wide) PHA were rammed by a fast moving 2 ton projectile, it would barely miss hitting the Earth… and this is talking 10 years in advance. In 1999, a special scale was created in the event that a PHA would threaten Earth. This is called the Torino scale, and was created in Turin, Italy. The scale goes from one to ten. One means that the potential PHA needs to be monitored, and 10 means that there will undoubtedly be a collision. This scale is also color coded with the colors white, green, yellow, orange, and red. The meanings of the colors are as follows: White: There is a very small chance that a PHA will collide with Earth. Should it happen, the PHA will do zero to no damage. This means that it either completely burns up when it enters the atmosphere, or has such a small impact that no damages or injuries will result. The white zone could also constitute a near collision, and not an imminent one. Green: Monitor carefully. There is a small chance that a PHA will collide with Earth. Should it happen, the PHA will do some damage, but not enough to be of great concern. Yellow: Concern: There is some chance that a PHA will collide with Earth. Should it happen, some injury and/or damage will occur. Under this event, there would be some concern of both human lives and damaged property. Orange: Threatening: There is a very high chance that a PHA will collide with Earth. Should it happen, the damage done by the PHA’s impact is no longer local, but has become regional or global. The entire world could be at risk of dust clouds, climate change, etc. Red: Collision imminent. A PHA that collides with the Earth will affect the planet on a global scale, and possibly wipe out civilization as we know it. There is no doubt that the Earth is still vulnerable from Near Earth Objects. Space is still so new to the human race despite all of the money and time used to study it. What lies beyond Pluto and the Oort cloud? Anything? Does space go on forever? Another question to raise concerns the creation of more asteroids and comets. How large would they be, and what orbit would they follow? Despite what humans do know about Near Earth Objects, there is still no sure way of moving them out of Earth’s path. No one knows what an explosion would do, or how it would react to the PHA. A shove or a nudge would have to be made well in advance, and even then the guarantee that it would completely miss the Earth is not certain. The human race is very much at the mercy of not just the Earth, but also the universe. Our days could well be numbered hundreds of years in advance. Respecting the world and the universe outside of it is all the human race can do for the moment. It deserves far more respect than we have offered in the past, and who knows… maybe one day it will demand it instead of simply asking nicely. Alexander, Mary. “The World’s Biggest Meteor Crater.” South African.info: Gateway to the Nation. South Africa. 2008. Web. 15 Mar. 2011. “Apophis: The Asteroid That Could Smash Into the Earth on April 13th, 2036.” Deep Astronomy.com: Better Living Through Astronomy. Darnell, Tony. Nd. Web. 16 Mar. 2011. “Asteroids.” Nine Planets. Nine Planets. 2010. Web. 16 Mar. 2011. “Comet.” The Encyclopedia of Science. The Worlds of David Darling. 2011. Web. 15 Mar. 2011. “Comets.” Solar System Exploration. National Aeronautics and Space Administration. 2011. Web. 15 Mar. 2011. “Famous Comets.” Comet Facts, Myths, and Legends. Comets. Nd. Web. 16 Mar. 2011. “Miracle Planet: Asteroid Impact Simulation.” World News. World News. 2011. Web. 16 Mar. 2011. 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