Generally the author has to savagely pound a square peg into a round hole, with regrettable results.
Astrogeology is Aliens of the ocean essay planetary science discipline concerned with the geology of celestial bodies such as the planets and their moonsasteroidscometsand meteorites. The information gathered by this discipline allows the measure of a planet 's or a natural satellite 's potential to develop and sustain lifeor planetary habitability.
An additional discipline of astrogeology is geochemistrywhich involves study of the chemical composition of the Earth and other planetschemical processes and reactions that govern the composition of rocks and soilsthe cycles of matter and energy and their interaction with the hydrosphere and the atmosphere of the planet.
Specializations include cosmochemistrybiochemistry and organic geochemistry. The fossil record provides the oldest known evidence for life on Earth. Some regions on Earth, such as the Pilbara in Western Australia and the McMurdo Dry Valleys of Antarctica, are also considered to be geological analogs to regions of Mars, and as such, might be able to provide clues on how to search for past life on Mars.
The various organic functional groups, composed of hydrogen, oxygen, nitrogen, phosphorus, sulfur, and a host of metals, such as iron, magnesium, and zinc, provide the enormous diversity of chemical reactions necessarily catalyzed by a living organism.
Silicon, in contrast, interacts with only a few other atoms, and the large silicon molecules are monotonous compared with the combinatorial universe of organic macromolecules. If life has had a comparable impact elsewhere in the Solar System, the relative abundances of chemicals key for its survival — whatever they may be — could betray its presence.
Whatever extraterrestrial life may be, its tendency to chemically alter its environment might just give it away. AbiogenesisLife on MarsLife on EuropaLife on Titanand Hypothetical types of biochemistry Europadue to the ocean that exists under its icy surface, might host some form of microbial life.
People have long speculated about the possibility of life in settings other than Earth, however, speculation on the nature of life elsewhere often has paid little heed to constraints imposed by the nature of biochemistry.
Only two of the natural atoms, carbon and siliconare known to serve as the backbones of molecules sufficiently large to carry biological information.
As the structural basis for life, one of carbon's important features is that unlike silicon, it can readily engage in the formation of chemical bonds with many other atoms, thereby allowing for the chemical versatility required to conduct the reactions of biological metabolism and propagation.
Thought on where in the Solar System life might occur, was limited historically by the understanding that life relies ultimately on light and warmth from the Sun and, therefore, is restricted to the surfaces of planets. Pyrimidine, like polycyclic aromatic hydrocarbons PAHsis the most carbon-rich chemical found in the universe.
Rare Earth hypothesis The Rare Earth hypothesis postulates that multicellular life forms found on Earth may actually be more of a rarity than scientists assume.
It provides a possible answer to the Fermi paradox which suggests, "If extraterrestrial aliens are common, why aren't they obvious? The Principle of Mediocrity suggests that life on Earth is not exceptional, but rather that life is more than likely to be found on innumerable other worlds.
The anthropic principle states that fundamental laws of the universe work specifically in a way that life would be possible. The anthropic principle supports the Rare Earth Hypothesis by arguing the overall elements that are needed to support life on Earth are so fine-tuned that it is nearly impossible for another just like it to exist by random chance.
Extraterrestrial life The systematic search for possible life outside Earth is a valid multidisciplinary scientific endeavor. It has been proposed that viruses are likely to be encountered on other life-bearing planets.
As of [update]no evidence of extraterrestrial life has been identified. At a microscopic level, spheres are found in the meteorite that are rich in carbon compared to surrounding areas that lack such spheres. The carbon-rich spheres may have been formed by biotic activity according to some NASA scientists.
Hoovera scientist with the Marshall Space Flight Centerspeculated on the finding of alleged microfossils similar to cyanobacteria in CI1 carbonaceous meteorites in the fringe Journal of Cosmologya story widely reported on by mainstream media. Methane Inthe spectral signature of methane CH 4 was detected in the Martian atmosphere by both Earth-based telescopes as well as by the Mars Express orbiter.
Because of solar radiation and cosmic radiationmethane is predicted to disappear from the Martian atmosphere within several years, so the gas must be actively replenished in order to maintain the present concentration.
Planetary systems It is possible that some exoplanets may have moons with solid surfaces or liquid oceans that are hospitable. Most of the planets so far discovered outside the Solar System are hot gas giants thought to be inhospitable to life, so it is not yet known whether the Solar System, with a warm, rocky, metal-rich inner planet such as Earth, is of an aberrant composition.
Improved detection methods and increased observation time will undoubtedly discover more planetary systems, and possibly some more like ours. For example, NASA's Kepler Mission seeks to discover Earth-sized planets around other stars by measuring minute changes in the star's light curve as the planet passes between the star and the spacecraft.
Progress in infrared astronomy and submillimeter astronomy has revealed the constituents of other star systems.
Planetary habitability Main article: Planetary habitability Efforts to answer questions such as the abundance of potentially habitable planets in habitable zones and chemical precursors have had much success. Numerous extrasolar planets have been detected using the wobble method and transit methodshowing that planets around other stars are more numerous than previously postulated.
The first Earth-sized extrasolar planet to be discovered within its star's habitable zone is Gliese c. Missions such as the Phoenix landerMars Science LaboratoryExoMarsMars rover to Mars, and the Cassini probe to Saturn 's moons aim to further explore the possibilities of life on other planets in the Solar System.
Viking program Main article:I. “Silliest internet atheist argument” is a hotly contested title, but I have a special place in my heart for the people who occasionally try to prove Biblical fallibility by pointing out whales are not a type of fish. Another great essay. I enjoy your writing so much Mr.
Kingsworth– its like having my innermost feelings, thoughts and ideas given voice in . Devil In The Dark () The Horta was an example of Silicon life.; Now we are really sailing off into terra incognito.
"Here be dragons" and all that. But if you have starships, you almost have to have aliens (Isaac Asimov's Foundation trilogy being the most notable exception).The "science" is called Astrobiology, the famous "science in search of a .
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Go to: Distributed Proofreaders. This is the full text of Ralph Waldo Emerson's essay, rutadeltambor.comn uses several words that are not in common use today. You'll find the definitions of those words by .