Life+on+Other+Planets?

//Life on other// //pla////nets//

Life on other planets, or extraterrestrial life, is defined as life which does not originate from earth.It is the subject of astrology and its existence remains hypothetical, because there is no credible evidence of extraterrestrial life. Several theories have been proposed about the possible basis of alien life from a biochemical, evolutionary or morphological viewpoint. In this world we still cannot define “life” but what we can do is know the circumstances’ that life needs to flourish. The requirements for life on a planet are; carbon, hydrogen, oxygen, nitrogen, sulfur and phosphorus. In a classical paper presented by G. Wald in 1964 to the US National Academy of Sciences, it was established that life requires: > It also requires water as the solvent in which biochemical reactions take place. Because Earth and some other planets are made up of "star dust", the subatomic particles of stars after they become supernovae, there is a good chance that there are other planets with the same make up. In addition to the biochemical theory there are also those who have considered evolution and morphology. In science fiction aliens are often depicted as somewhat humanoid beings with big heads, four limbs, and green or light gray skin. There is a division between universal and parochial (narrowly restricted) characteristics. Universals are features that are necessary for life, and have evolved more than once, independently on earth. These would include sight, flight, photosynthesis, and limbs. Parochial however, are essentially unnecessary forms. These often have inherent utility and will probably not be replicated. For example, aliens could communicate in sign language the way some deaf humans do, or they could speak in a way not related to breathing, such as cicadas do when they rub there legs together.
 * 1) the presence of [|liquid water] ;
 * 2) the [|elements] needed for metabolism and reproduction;
 * 3) a [|source of energy] ;
 * 4) suitable [|environmental conditions].

 ====Beliefs in extraterrestrial life may have been present in ancient India, Babylon, Assyria, Sumer, Egypt, Arabia, China and South America, although in these societies, cosmology was often associated with the supernatural, and the notion of alien life is difficult to distinguish from that of gods, demons, and such. The possibility of alien life remained a wide spread speculation as scientific discovery accelerated. Many astronomers of the 18th-19th century were sure that our galaxy was teaming with alien life. At the height of the excitement, event the sun and the moon were thought to be probable hosts for alien life. The enthusiasm of extraterrestrial life continued well on into the 20th century. In fact, the three century's from the scientific revolution through to the beginning of the modern era of solar system probes were pretty much the take off point for extraterrestrial beliefs in the west. Many scientific minds, the minds of the churches and most of the public were largely satisfied that aliens were a reality.==== =Drakes Equation:= Drakes Equation states that: The Drake equation (also sometimes called 'The Green Bank equation', 'The Green Bank Formula' or often erroneously labelled 'The Sagan equation') is a famous result in the speculative fields of exobiology and the search for extraterrestrial intelligence (SETI).  Source: [|Drake équation] Dr. Frank Drake used this equation to determine that there are roughly 10,000 planets containing life. Based on observations from the Hubble Space Telescope, there are at least 125 billion galaxies in the universe. It is estimated that at least ten percent of all sun-like stars have a system of planets, there are 6.25*1018 stars with planets orbiting them in the universe. If even a billionth of these stars have planets supporting life, there are some 6.25 billion life-supporting solar systems in the universe. So as you can see, Drakes equation is a little bit off. The Drake equation is a mathematical formula which defines how many civilizations are in the milky way **N = R* fp ne fl fi fc L **  where, >  So far Drakes equation estimates 10,000 communicative civilizations in the Milky Way. This is relivant because now we are trying to find other worlds and communicate with other life forms! Right now there is a 99.9 % chance that life exists.
 * The rate of formation of suitable stars.
 * The fraction of those stars which contain planets.
 * The number of Earth-like worlds per planetary system.
 * The fraction of planets where intelligent life develops.
 * The fraction of possible communicative planets.
 * The “lifetime” of possible communicative civilizations.
 * **N** = The number of communicative civilizations
 * **R*** = The rate of formation of suitable stars (stars such as our Sun)
 * **fp** = The fraction of those stars with planets. (Current evidence indicates that planetary systems may be common for stars like the Sun.)
 * **ne** = The number of Earth-like worlds per planetary system
 * **fl** = The fraction of those Earth-like planets where life actually develops
 * **fi** = The fraction of life sites where intelligence develops
 * **fc** = The fraction of communicative planets (those on which electromagnetic communications technology develops)
 * **L** = The "lifetime" of communicating civilizations

Their have been several “sightings” of ufo’s and aliens but unfortunately we cannot prove it because The government has covered it all up if there was any proof to begin with.

**B**ibliography:
Wikipedia Space.com []

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