Argument

Life Beyond Our Planet

 One of the questions that have long intrigued humanity is whether or not Earth is the only planet inhabited by life. Although we have no concrete evidence, and in turn, no actual proof of the existence of life, whether simple or more intelligent, there is still enough logic behind the theories to make many believe. With a Universe as vast as it is, and so rich with life forming elements, while also taking into account the organisms on our Earth with the ability to survive extreme environments, it is quite possible that life may exist, or once existed, beyond our planet.

As Greek philosopher Metrodorus of Chios once wrote, "It is unnatural in a large field to have only one shaft of wheat, and in the infinite Universe only one living world" (Achenbach). Metrodorus’s loosely reiterates the idea that the universe being as vast in size as it is creates the possibility that life may be sprinkled throughout it. There is an unimaginable amount of stars within the universe, many of which are likely to have several planets orbiting around it, creating a model of our own life bearing solar system. There are estimated to be “400 billion stars of various sizes and brightness” just within our Milky Way galaxy alone (Cain). Since its launch in 2009, NASA's Kepler space observatory has “discovered two new planetary systems that include three super-Earth-size planets” within what can be described as the "habitable zone" (Johnson). The habitable zone is defined by Johnson as being the range of distance the planet is from the sun that makes it suitable for liquid water. The two newest discovered earth-like planets orbit in a 5 planet system around the star Kepler-62, which is described to be a bit smaller in size, and in turn cooler, than the sun (Water Planets in the Habitable Zone).  One of these recently discovered planets include Kepler-62e, a planet about 60 percent larger than the Earth and is thought by Harvard astronomer Dimitar Sasselov to “probably [have] a very cloudy sky and [be] warm and humid all the way to the Polar Regions” (Water Planets in the Habitable Zone). The other Super-Earth planet was named 62-f and is roughly estimated to be 40 percent larger than earth. Sasselov also describes this planet as being “cooler, but still potentially life-friendly” (Water Planets in the Habitable Zone). Both of these planets are expected to be composed of rock and completely covered in ocean and both have a relatively similar orbit length, with Kepler-62e’s orbit lasting 122 days and Kepler-62F’s lasting an even more similar period of 267 days (Johnson). These recent discoveries of two seemingly inhabitable planets within our galaxy based around one star in out Milky Way highlight the potential for numerous more planets that life could inhabit. (Based on the similarities of these new worlds to our own home planet, it is possible that a simple small living microbe or even a more advanced form of life could inhabit them.)

Though life-forms on earth may differ in a multitude of ways, they all have one thing in common: each and every one is categorized as carbon based. According to Doctor Neil deGresse Tyson, the three elements “hydrogen, oxygen, and carbon account for over 95% of the atoms in the human body and all known life” (Tyson). These three elements he refers to which formulates most life just so happens to also be the universes most abundant elements. We are considered to be carbon-based life because carbon is considered the most active element, in which the structure enables carbon to form strong bonds with both itself and with other elements (Tyson). It is well know that at the end of their life stars often explode, sending the elements they have created out into space. These elements at one point came together, forming compounds and evolved from single cells into to create life as we know it today. Knowing that this explosion, or death of a star, is not an uncommon event, it could be suggested that the elements bursting from these stars could have come together in a similar way to create a different forms of life. If life on Earth is created from elements that can be found in abundance throughout the universe, then it is also possible that life created on other planets could also be carbon based. If life on Earth was comprised of more uncommon ingredients, than it would be harder to justify life beyond our own planets, but instead we are created from un-special components which helps to raise the possibility of extraterrestrial life.

There are several examples of micro-organisms found here on our own home planet that exhibit the ability life has to survive even the harshest of extremes. Assuming current life originated on Earth, it had to have formed in intense conditions such as hot magma, changes to the atmosphere and physical structure of the Earth, meteors and extreme drops in temperature. During the 1990s, basaltic rock deep beneath Washington State was found to contain an “abundance of microbes totally cut off from the photosynthetic world” (Achenbach). Similarly in existence is a deep sea microbe named a "Methanogen” which is “an organism that inhales hydrogen and carbon dioxide,” surviving completely independent of oxygen (Dvorsky). Even more extreme than the Methanogens is the Tardigrade. These tough microscopic creatures have been “reported to live more than 100 years without food and water” and been known to survive pressures “as low as the vacuum in outer space and as high as 6x the pressure of the deepest part of the ocean” (Brown). It has been speculated that deep beneath a layer of thick ice, Jupiter’s moon Europa holds a frigid ocean, which could be inhabited by creatures’ similar to the microbe found beneath a lake in Antarctica. These organisms are sealed under a 50-foot ice cap and are able to survive despite the -13°C temperature, lack of oxygen, light and pH of 6.2 (Barribeau). Extremophile is the name given to organisms that have the ability to combat most of the hardships mentioned previously, such as extreme temperature, vacuums, and chemicals that are poisonous to most other life-forms (What Is an Extremophile). Through the research of these tenacious creatures, we can only better our knowledge of what could be living in the harsh environments’ beyond our planet.

Though humanity has not currently found any facts pointing directly to the existence of life-forms beyond our planet, scientists are continuously searching. For now, scientist have to base the possibility on a few supporting ideas, such as the size of our universe, the universal ingredients of life here on Earth, and the ability for microscopic organisms to survive severe environments. There is no doubt that the search for life will continue, and like Carl Sagan said: “Absence of evidence is not evidence of absence.”

Bibliography

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Johnson, Michele. "Astrophysicists Find Five-Planet System with Most Earth-like Exoplanet Yet." Astrophysicists Find Five-planet System with Most Earth-like Exoplanet Yet. N.p., 18 Apr. 2013. Web. 19 Oct. 2013. <http://phys.org/news/2013-04-astrophysicists-five-planet-earth-like-exoplanet.html>.

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