Comets and asteroids

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Table of Contents

Introduction
The Threat to Human Life
The way forward
Conclusion
References

Introduction

Bodies that orbit the sun face many threats posed by crashing asteroids and comets. Scientific investigations have revealed that comets and asteroids which orbit the sun sometimes alter their orbital trajectory, disintegrate into fragments, and pose the kind of threat that caused the extinction of dinosaurs millions of years ago when an asteroid crashed into the earth.

Potential Impact

Gabor (1995, p. 1) states, “Asteroids are rocky and metallic objects that orbit the Sun but are too small to be considered planets’’. Gabor (1995) coins the term “minor planets” being descriptive of the fast moving rocky metallic objects with the potential of crashing into the earth with disastrous results.

These metallic objects vary in size ranging from several hundreds to a thousand kilometers in diameter. Scientific research indicates that a single asteroid or comet 10 kilometers in diameter has the capacity to cause widespread destruction in the event of a collision with the earth. Early discoveries indicated that comets, which encountered Jupiter’s gravitational pull, experienced celestial tidal waves, which could deflect the fast moving metallic objects into a collision course with the planet.

Atkinson (1999) asserts that the possibility of a comet or an asteroid hitting the earth is rife. Atkinson (1999) argues, “…our planet gets hit by a 10 kilometer diameter (about 7 miles) comet or asteroid every hundred million years on average”. Observations have shown that asteroids frequently stray into the earth’s atmosphere and burn up without causing any harm. In addition, they frequently enter Jupiter’s atmosphere with similar results.

Atkinson (1999) argues that in the event of a collision with the earth, a blanket of dust could cover the earth, a near darkness situation could ensue, normal plant and animal chemical activities could stop due to lack of sunlight and if the situation persists for months, most of the species on earth could be extinct.

Atkinson (1999) argues that the frequency with which asteroids crash into the earth’s atmosphere expressed mathematically shows an inverse relationship with size. The article NEA Population and Impact Frequency (2001), asserts that a crash with the earth depends on their population density and proximity to the earth. The impact of an asteroid, according to the article, Asteroid on Collision Course with Earth (2010), depends on its angular velocity caused by a deflection by the earth’s gravitational pull on the orbiting rock.

Calculations have provided reliable estimates, which indicate that if a 5-meter diameter asteroid enters the earth’s atmosphere it may explode with a force equivalent to that of an atomic bomb. Scientific observations indicate that these explosions are quite frequent and take place in the earth’s upper atmosphere without causing any damage.

Arnett (2008) notes that asteroids move at speeds in the range of 100,000 km/hr. when it enters the earth’s atmosphere, friction with the upper layers of the atmosphere causes intense heat in the range of thousands of degrees centigrade causing the asteroid to disintegrate with a powerful explosion releasing large amounts of energy.

The probability of an asteroid or comet hitting the earth is measured on a albedo scale. According to the article NEA Population and Impact Frequency (2001), asteroids with a value whose absolute magnitude of albedo is less than 1 km are classified in the range of I to 14500 of colliding with the earth while asteroids with a diameter of 1.5 km have a 1 in 10500 chance of colliding with the earth. Based on these probabilities, the potential threat of a catastrophic event due a collision remains a rare event.

The dynamic natures of the orbital trajectories of these rocky objects coupled with the frequency with which they collide with the earth assert the possibility of a disastrous collision (NEA Population and Impact Frequency 1). Astrophysicists have researched and pointed out such collisions are likely to happen separated by a time span ranging in millions of years.

The report asserts, “…the new impact risk estimate, like most previous ones, relies on assumptions about a single event 65 million years ago when a 10-kilometer asteroid collided with earth and killed the dinosaurs. The researchers have assumed that such impacts occur roughly a 100 million-year interval.

They used that statistic to calculate the impact odds for the more common asteroids of smaller sizes” (NEA Population and Impact Frequency 2001, p.1). This shows clearly the kind of energy stored in these moving bodies and the potential consequences in the event of a collision with the earth.

Life on Earth Threatened

Arnett (2008) argues that a lot of evidence abounds on the moon’s surface of depressions caused by meteorites hitting the surface of the moon. The resulting craters when observed bares evidence of the kind of impact that could occur on the earth in the event of such a collision.

Astronomers have discovered many asteroids to be heading towards the earth with high chances of crashing into the earth. According to Atkinson (1999), asteroid 2002NT7’s trajectory was reportedly inclined on the earth’s axis in space; heading towards the earth and believed to be of the size that could cause extinction of life on earth in the event of a crash. However, scientists allayed fears concerning the potential impact of the rock when further investigations revealed that collision chances were rare.

Other discoveries have identified asteroid QQ347 with a diameter of 1.2 km and smaller in size than the previous asteroid and is projected to strike the earth in 2014 (Atkinson 1999). Despite this discovery, scientists have urged calm arguing that several observations will clarify the final position taken by the scientific community regarding the course of this asteroid. However, Atkinson (1999) argues that the potential hazard of this asteroid is worthy contemplating.

Binzel (1999) summarizes the potential risks associated with varying levels of collisions on a Torino scale. This scale is used to asses the impact of an asteroid in analyzing the likely hazards due to an impact resulting from such collisions. Torino is a ten-unit scale calibrated from zero to ten.

When a collision lies in the zero range, the impact is non-hazardous. According to Binzel (1999) collisions on Torino scale one are normal, scale two to four merits attention from astrophysicists and astronomers, five to seven are threatening collisions, and those in the range of eight to ten have the probability of occurring (Binzel 1999). Barbara (2004 compares a collision of this kind to the equivalent of 20 million Hiroshima atomic bombs. That could be enough to clear the earth of any living animals and plant activities.

Dinosaurs Extinction

Various theories regarding the extinction of Dinosaurs abound. Many theories have however proved extinct except the theory relating to the impact of an asteroid. Based on scientific data from various studies, certain metallic elements characteristic of meteorites buried within craters found on earth are suggestive of a destructive meteoritic event.

According to Barbara (2004), these chemical compositions include iridium. Iridium is a rare earth element but forms a composite percentage of a meteorite or a comet providing further and detailed evidence of the possibility that a meteorite collided with the earth causing the extinction of dinosaurs.

In addition to all these, the discovery by Bruce Bohor and other colleague of shocked quartz was characteristic of an element subjected to intense heat suggesting persistently high temperatures on a global scale. This temperature on a global scale was likely caused by the remnants of a comet or an asteroid, which crashed onto the earth causing a sudden rise in temperature and other unbearable climatic conditions.

The article, Asteroid Impacts and Meteor Impacts (2010) compares the size of a planetoid required to destroy a large city to an equivalent size of a small garage. This study illustrates what might have happened to dinosaurs in the event of such a collision. According to Asteroid Impacts and Meteor Impacts (2010, p.1)

“It is thought that 65 million years ago in what is now Yucatan the impact at a velocity of 11 km/second of a 10-kilometer wide asteroid is what helped to bring about the K-T extinction, whereas no land animal with a size greater than the size of a small chicken was able to survive.”

The resulting conditions from this collision made the earth uninhabitable. The article, Asteroid Impacts and Meteor Impacts (2010) continues to analyze the conditions at the time, asserting that several months of severe weather conditions and darkness might have followed.

The analysis indicates that amino acids could not survive in such climatic conditions and temperatures. According to the article, Dinosaur Extinction Page (1996) the Asteroid theory points to an impact as the most likely cause of the destruction based on an analysis of a layer of soot found on a rock identified as an asteroid.

The Near Earth Object Program (2010) points out that the soot resulted from fires due to the strong impact or collision on the earth by a near to earth object (NEO). Characteristics of physically altered quartz crystals talk of extreme pressures and temperatures within the environment at the time. The colliding objects might have had a velocity of 100,000 km/h to cause such destruction, the magnitude of 10,000 nuclear bombs’ detonated simultaneously. The earth at those temperatures could not have sustained life (Verschuur, 1996).

Various theories have been formulated regarding the chemical compositions of crashing asteroids at the site of these impacts. On of them is the Alvarez theory. According to the theory, unique chemical elements were identified to be in different layers of rocks at the crash site pointing to the start of the Tertiary period (DINOSAUR EXTINCTION 1996).

Investigations identify the chemical elements in the discovered rocks. “It is divided into two layers, the Magic Layer (3 mm thick) and the Ejecta Layer (2 cm thick).” DINOSAUR EXTINCTION (1996, p.1) notes that siderophiles, which constitute rare earth elements, are predominant in asteroids pointing to a potential collision on the earth. These elements discovered at various regions included New Zealand, Denmark, and Italy providing ample evidence pointing to the cause of the extinction. Other chemical elements evident in these layers were iridium, Tektites, shocked quartz, and silicon dioxide.

These elements make a big percentage in composition of the metallic and rocky meteorites. DINOSAUR EXTINCTION (1996, p. 1) states “severe storms with high windsand highly acidic rain, seismic activity, and perhaps even volcanic activity. The impact could have caused chemical changes in the Earth’s atmosphere, increasing concentrations of sulfuric acid, nitric acid, and fluoride compounds. The heat from the impact’s blast wave would have incinerated all the life forms in its path.”

The Threat to Human Life

The answer to the question of the likely event of a cataclysmic event has all probabilities of occurring. Fossil and astronomical research identifies the potential nature of such collisions (New Asteroid Threat to Earth 2010). Despite the protective shield provided by the earth’s atmosphere, many NEOs’ remain unidentified and this places the earth at a high risk of a crash.

In addition, the article The Tunguska Event (2008) points to enormous explosions in the earth’s atmosphere due to disintegrating asteroids. This could be in addition to discoveries by astronomers of blind spots in space. It is has been asserted that an asteroid moving in this region may go undetected and eventually strike the earth without warning. Atkinson (1999) sees the destructive possibility overwhelming.

The way forward

To help confront any potential threat to the human race, it could be prudent upon scientists to identify objects that may be on a collision course with the earth. Concerted effort by politicians, scientists and engineers could help device means of detecting the course of these meteorites and comets and device means of countering or deflecting them from their path to avert disaster.

A planetary defense council held on 27-30 April 2009 reinstated the need for such technologies to avert such a disaster. The council identified the need for early assessment and evaluation of consequences due to a collision and ways of addressing them. The conference proposed policies formulations as fundamental to dealing with the impeding problem. According to the article Planetary Defense Conference (2009), statistical analysis is vital to assess hazards related to such impacts.

In addition to innovative ways of mitigating the hazards and handling public concerns, the article proposes that small and large asteroids should be deflected off course to avert any risks associated with any potential impacts. According to the Near Earth Object Program (2010), recent discoveries of asteroids have gained momentum. These include the 2010 GA6 asteroid that will pass by the earth, asteroid 2010 AL 30 will fly by in a distance of 76,000 miles.

Conclusion

Controversy surrounds the perplexing question of the destruction of dinosaurs. However, fossil, mineral, and rocks provide evidence pointing to a destructive asteroid as the potential annihilating force of the animals’ lives some 65 million years ago. To help avert such a threat to life on earth, it is important for the scientific community to create technologies to deflect these asteroids. Asteroids and comets should be treated as our common.

References

Arnett, B., 2008. Asteroids. Web.

Asteroid On Collision Course With Earth. 2010. Web.

Atkinson, A., 1999, Impact Earth? Asteroids, comets and meteors? The Growing Threat `Virgin, London.

Barbara, S., 2004. Evidence Of Meteor Impact Found Off Australian Coast. Web.

Binzel, R. P., 1999-2004. Torino Impact Scale. Web.

DINOSAUR EXTINCTION. 1996. Web.

Near Earth Object Program. 2010. Web.

NEA Population and Impact Frequency. 2001. Web.

New Asteroid Threat to Earth. 2010. Web.

Verschuuur, G. L., 1996. Impact! 1996 The threat of comets and asteroids. Oxford University Press, New York.

Planetary Defense Conference. 2009. Web.

The Tunguska Event, 2008. Web.

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