The Earth is the only gift the universe has given to man.Dated back to about 4.5 billion years ago,it has a shape,described as geoid,as distinct from a sphere,but have a much more closer resemblance to what is called “an oblate spheroid.” Uniquely the third planet in the solar system,the planet Earth is the only planet habitable by man in the “The Milky Way .”
Different cultures of the world have one thing or the other to say about the origin and form of our dear planet,and both oral as well as written ideas are well-known.However,no one has been able to surpass the creativity and ingenuity of scientists.Science has come with a much more better perception of the planet.Now,we know that the planet Earth is a product of some successive stages,like it is found in man and other other life forms,known as evolution.The planet Earth is known to have evolved from a combination of particles and dusts,also known as “solar nebula,” which was formed as a result of a spontaneous action,the details of which more research is still required to elucidate.For now,the spontaneous action is thought to be the results of a gravitational collapse of a giant molecular cloud.
What’s more?The Earth is not alone in the evolution process,as other planets are also known to have evolved similarly.
What then is space dust?Space dust,also called cosmic dust,consists of dust grains and aggregates of dust grains,irregularly shaped,and highly porous.Their composition depends on where they are found,and could be realized by doing a compositional analysis.As they arrive in the Earth’s atmosphere,cosmic dust is charged with helium atom by solar wind. Cosmic dusts have radiative properties,which could be detected by both direct and indirect methods.Only recently,scientists have confirmed the presence of a slow steady rain of cosmic space dust always falling through the Earth’s atmosphere.A record dated back to 30,000 years was uncovered in an ice core in Antarctica.
At the inception of astronomy,space particles and dusts appeared to be a burden to astronomers who were only interested in using telescope to watch distant stars and galaxies,because such particles tend to block their vision,a situation which render visibility to almost zero.But quite unknown to them,the same dust that poses visibility problem,is perhaps the single most important source of the information they are looking for about the planet Earth,other planets,and the entire universe.Discovering the truth about space dust changed the course of astronomy,as astronomers eventually discovered there is a huge relationship between the planet Earth and cosmic dust.
It is now well-known that space dust play a major role in the formation of planets.Scientific evidence has justified the formation of various planets from the solar nebula,the disc-shaped cloud of gas and dust left over from the formation of the Sun.Currently,planets are believed to be formed by a method known as “accretion,” in which a planet begins its development as dust grains in orbit around a central protostar.These grains continue to grow in size through direct contact with other dusts.A gigantic particle or body eventually forms,with a diameter in the region of about 10,000 km.Accretion is not localized,so other bodies are formed also.These in turn collided to form larger bodies with average diameter equal to 4.8 km.These bodies are called planestesimals.The growth process is never stopped,but rather continues,buiding mass along the way,over the the next few million years.
The relationship between the Earth and space dust still has another extension,in the name of stardust.Stardust is thought to be a modest fraction of the condensed cosmic dust,with a mass lower than 0.1 percent of the total mass of interstellar solids.The beauty of stardust lies
in the fact that each grain existed before the earth was formed.Cosmochemists found carbonaceous chondrites a very fertile reservoir of stardust,and have identified many
different types of stardust.This feat was achieved by laboratory measurement of the highly
unusual isotopic composition of the chemical elements comprising each grain.The wealth of information now available to mankind through nucleosynthesis and stellar evolution is sufficient proof to justify the bond between space dust and the entire universe.To shed more light,nucleosynthesis is the process by which new atomic nuclei are created from pre-existing protons and neutrons.And when a star undergoes a sequence of radical changes during its
lifetime,the process is called stellar evolution.
Moreover,space dusts are also known to scatter light nonuniformly,but the effect of this is still a field of further scientific investigation,most especially as it affect all lifeforms
on Earth,mankind inclusive.
Finally,the nebular hypothesis,developed in the 18th century,by the trio of Immanuel Kant,Pierre-Simon Laplace,and Emmanuel Swedenborg has opened up many challeging fields
involved in the study of the solar system,the universe,and even extraterrestrial bodies.Now we know the planet Earth was formed from particles and dusts. In a way,the “particle and dust concept” seems to be winning,and it seems a complete appraisal of the planet Earth will be practically impossible without an input of space dust.
Sources
http://en.wikipedia.org/wiki/Earth
http://www.geotimes.org/apr05/NN_spacedust.html
http://en.wikipedia.org/wiki/Cosmic_dust
http://en.wikipedia.org/wiki/Solar_nebula#Formation_of_planets
http://www.universetoday.com/2006/08/07/constant-rain-of-space-dust-adds-up/
http://en.wikipedia.org/wiki/Stellar_evolution
