Our Universe The Cradle Of Life Essay
While the free essays can give you inspiration for writing, they cannot be used 'as is' because they will not meet your assignment's requirements. If you are in a time crunch, then you need a custom written term paper on your subject (our universe the cradle of life)
Here you can hire an independent writer/researcher to custom write you an authentic essay to your specifications that will pass any plagiarism test (e.g. Turnitin). Waste no more time!
When considering the likeliness of life arising repeatedly throughout our universe, the first three terms of the Drake Equation immediately come to mind. Since life needs a place to arise, the availability of such places becomes one of the most important considerations. Even though the rate of star formation is currently not determined exactly, based on evidence, it could be estimated to be relatively high. In our own galaxy, star formation can be observed in the frontal areas of the spiraling arms, where abundant quantities of gas and dust become more concentrated due to the rotation of the galaxy. There are constantly stars being born inside galaxies and considering the existence of about 100 billion galaxies in our universe, it is logical to assume that the rate of star formation is extremely high. Even if only 1000 stars form per galaxy per year, it would mean that 100 trillion stars form in our universe per year. Not all areas around the formed stars are suitable for supporting life. For life as we know it to exist, liquid water has to be available. Based on the inverse square law, both the luminosity of the star and the distance away from it go into figuring out the "habitable zone" in a particular solar system. Also the fact that stars' luminosities change as the stars go through their main sequence has led to decreasing the "habitable zone" into a "continuously habitable zone". A planet located in the continuously habitable zone is considered able to maintain liquid water on its surface. Of course surface conditions like temperature, pressure, albedo, and the greenhouse effect also strongly contribute to the individual planet's ability to maintain surface water in liquid state. Stars with spectral types of G and K are considered to have large enough habitable zones and long enough main-sequence times for the formation of life. Based on observations in our own galaxy, approximately 22.3% (15% are K, 7.3% are G) of all the stars forming in our universe fall in the G and K classification categories. Considering the calculation mentioned earlier, with which it was determined that around 100 trillion stars form in our universe per year, it could be derived that 22.3 trillion stars capable of supporting life form every year. The number could be increased even further if microscopic life, instead of complicated life is the one being considered. Since it only took approximately 1.5 billion years after the formation of our sun for microscopic life to form on Earth (3.5 million-year-old fossils), brighter stars with shorter main-sequence spans, but larger habitable zones could be considered as places where life can arise. Stars with main-sequence life spans of 1.5 billion and above would become possible sites of life. If this approach is taken, an overwhelming majority of stars can be considered as capable of supporting life. Since life is incapable of surviving in the extreme environment on the surface of a star, planets orbiting around that star are the obvious place for life to be found. Two questions immediately arise when considering planets in other solar systems. Is it common for stars to have planets and if stars do have planets, how many are "earth-like"? Planet formation is in many ways similar to star formation. And why should it be different? The same laws of physics are in effect except on a smaller scale. Terrestrial planets are formed when gravity brings together small particles and dust left over in the accretion disk of the star until enough of them collide together to form planetesimals and then planets. The formation of the Jovian planets is even more similar to star formation because when they form, aside from the collisions of icy planetesimals found in the further-out regions of the solar system, these planets are massive enough to form their own mini-accretion discs. These mini-accretion disks can then go one step further and form moons such as the ones orbiting Saturn and Jupiter. Since it has been observed that all stars have accretion disks when they form, it can be deduced that the overwhelming majority of stars does have planets orbiting around them. Also, other solar systems containing planets have already been detected (41 UMa, 51 Peg, 70 Vir, etc.) and in our own solar system we observe several levels of planet formation (sun has planets, Jovian planets have moons). Based on the observations of the facility of planet formation in our own solar system and having no reason to believe that other stars' accretion disks would be much different from our own, it could be assumed that planets form with relative ease and that nearly all stars have planets. It is not enough to just have planets to have life. In order to support life, the planets have to be "earth-like". Meaning that they are located in a habitable zone and have the right surface conditions to have liquid water. If we only concentrate on the stars most likely to harbor life it would mean ignoring stars with spectral types other than G and K. These stars have either shorter main sequence times, enough for only microscopic life to form or too small of a habitable zone as in spectral type M. Considering the earlier calculation which gave us 22.3 trillion stars capable of supporting life forming every year and decreasing that number by a fraction to account for...
MLA Style
. EssayMania.com. Retrieved on 16 May, 2012 from
<http://essaymania.com/102086/our-universe-the-cradle-of-life>
More College Papers
Our Right To Bear Arms essay
18 November 1998Our Right to Bear Arms Gun prohibitionists would have you think that the only legitimate purpose for owning a firearm is "sporting purposes" such as hunting or target shooting. However, the Second Amendment was not included in the Bill of Rights so people could go duck hunting or pu
Oskar Schindler essay
With the near destruction of a Jewish nation came the rebuilding of a unifiednation, it may not had been the one that Hitler had envisioned , but it was onethat brought to us understanding, a gift that should never be looked downupon. That gift was bestowed to some even before we knew it existed. Os
Orwell's Influences essay
Orwell was influenced by many things including eventsin his life and the idea of totalitarianism. Theseinfluenced his writing of the book 1984. Orwell began life with the name of Eric Blair. Blairknew by the time he was four or five that he wanted to be awriter. Like his character in Winston Smi