A 1967 Soviet Union 16 kopeks stamp, with a satellite from an imagined extraterrestrial civilization. The Union of Soviet Socialist Republics (USSR was a constitutionally Socialist state that existed in Eurasia from 1922 to 1991 The ruble or rouble (рубль see below for other Soviet languages) was the currency of the Soviet Union.

Extraterrestrial life is life originating outside of the Earth. Life is a state that distinguishes Organisms from non-living objects such as non-life and dead organisms being manifested by growth through Metabolism EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 It is the subject of astrobiology, and its existence remains hypothetical. Astrobiology (from Greek grc ἄστρον astron, "constellation star" grc βίος bios, "life" and grc -λογία There is no credible evidence of extraterrestrial life that has been widely accepted by the scientific community. The scientific community consists of the total body of Scientists its relationships and interactions There are several hypotheses regarding the origin of extraterrestrial life. One proposes that its emergence occurred independently, in different places in the universe. An alternative hypothesis is panspermia, which holds that life emerging in one location then spreads between habitable planets. Panspermia ( Gk. πάς/πάν (pas/pan all and σπέρμα ( sperma, seed is the Hypothesis that "seeds" of Life exist already Planetary habitability is the measure of a Planet 's or a Natural satellite 's potential to develop and sustain Life. These two hypotheses are not mutually exclusive. In simple terms two events are mutually exclusive if they cannot occur at the same time (i The study and theorization of extraterrestrial life is known as astrobiology, exobiology or xenobiology. Speculative forms of extraterrestrial life range from sapient beings to life at the scale of bacteria. Sapience is often defined as Wisdom, or the ability of an organism or entity to act with appropriate judgment. The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have

Suggested locations that might have once developed or continue to host life include the planets Venus^[1] and Mars, moons of Jupiter and Saturn (e. The VENUS ( V ictoria E xperimental N etwork U nder the S ea project is a cabled sea floor observatory operated by the University g. Europa,^[2] Enceladus and Titan). TemplateInfobox Planet.--> Europa (jʊˈroʊpə; or as TemplateInfobox Planet.--> This article is about the moon of TemplateInfobox Planet.--> Titan (ˈtaɪtən, or as Gliese 581 c and d, recently discovered to be near Earth-mass extrasolar planets apparently located in their star's habitable zone, and having the potential to have liquid water. Gliese 581 c (ˈgliːzə is a " Super-earth " Gliese 581 d (ˈgliːzə is an Extrasolar planet approximately 20 Light-years away in the Constellation of Libra. An extrasolar planet, or exoplanet, is a Planet beyond the Solar System, orbiting around other Stars As of September 2008 312 In Astronomy a habitable zone ( HZ) is a region of space where conditions are favorable for Life as it may be found on Earth. ^[3]

Possible basis of extraterrestrial life

Biochemistry

Main articles: Biochemistry and Alternative biochemistry

All life on Earth your mom is an alien! is made up of the principal elements carbon, hydrogen, oxygen, nitrogen, and phosphorus; it also requires water as the solvent in which biochemical reactions take place. Biochemistry is the study of the chemical processes in living Organisms It deals with the Structure and function of cellular components such as Alternative biochemistry is the speculative Biochemistry of alien Life forms that differ radically from those on Earth. Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 Phosphorus, (ˈfɒsfərəs is the Chemical element that has the symbol P and Atomic number 15 Water is a common Chemical substance that is essential for the survival of all known forms of Life. A solvent is a liquid or gas that dissolves a solid liquid or gaseous Solute, resulting in a Solution. Sufficient quantities of carbon and the other major life-forming elements along with water may enable the formation of living organisms on other planets with a chemical make up and average temperature similar to Earth. Because Earth and other planets are made up of "star dust" ie, relatively abundant chemical elements formed from stars which have ended their life as supernova, it is very probable that other planets may have been formed by elements of a similar composition as Earth. A chemical element is a type of Atom that is distinguished by its Atomic number; that is by the number of Protons in its nucleus. A supernova (plural supernovae or supernovas) is a stellar Explosion. The combination of carbon and water in the chemical form of carbohydrates (e. Carbohydrates (from ' Hydrates of Carbon ' or saccharides ( Greek σάκχαρον meaning " Sugar " are the most g. , sugar), can be a source of chemical energy on which life depends, and also provide structural elements for life (such as ribose, in the molecules DNA and RNA and cellulose in plants). Sugar is a class of edible Crystalline substances mainly Sucrose, Lactose, and Fructose. In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός Ribose (ɹˈaɪbəʊs ɹˈaɪbəɹʊs primarily seen as D-ribose, is an Aldopentose — a Monosaccharide containing five Carbon Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known Ribonucleic acid ( RNA) is a Nucleic acid that consists of a long chain of Nucleotide units Cellulose is an Organic compound with the formula, a Polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4 Plants derive energy through the conversion of light energy into chemical energy via photosynthesis. Plants are living Organisms belonging to the kingdom Plantae. Photosynthesis is a Metabolic pathway that converts Light Energy into Chemical energy. Life requires carbon in both reduced (methane derivatives) and partially-oxidized (carbon oxides) states. It also requires nitrogen as a reduced ammonia derivative in all proteins, sulfur as a derivative of hydrogen sulfide in some necessary proteins, and phosphorus oxidized to phosphates in genetic material and in energy transfer. Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 Ammonia is a compound with the formula N[[hydrogen H3]] It is normally encountered as a Gas with a characteristic pungent Odor Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 Hydrogen sulfide (or hydrogen sulphide) is the Chemical compound with the formula H 2 S. Phosphorus, (ˈfɒsfərəs is the Chemical element that has the symbol P and Atomic number 15 A phosphate, an Inorganic chemical, is a salt of Phosphoric acid. Adequate water as a solvent supplies adequate oxygen as constituents of biochemical substances.

Pure water is useful because it has a neutral pH, due to its continued dissociation between hydroxide and hydronium ions. pH is the measure of the acidity or alkalinity of a Solution. In Chemistry, hydroxide is the most common name for the diatomic Anion OH− consisting of Oxygen and Hydrogen In Chemistry, hydronium is the obsolete name for the Cation H 3 O + derived from Protonation of Water An ionic bond (or electrovalent bond) is a type of Chemical bond that can often form between Metal and Non-metal Ions (or As a result, it can dissolve both positive metallic ions and negative non-metallic ions with equal ability. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Furthermore, the fact that organic molecules can be either hydrophobic (repelled by liquids) or hydrophilic (soluble in water) creates the ability of organic compounds to orient themselves to form water-enclosing membranes. In Chemistry, hydrophobicity (from the combining form of water in Attic Greek hydro- and for fear phobos) refers to the physical property of Hydrophile, from the Greek (hydros "water" and φιλια (philia "friendship" refers to a physical property of a Molecule MembraneA biological membrane or biomembrane is an enclosing or separating Amphipathic layer that acts as a barrier within or around a cell. The fact that solid water (ice) is less dense than liquid water also means that ice floats, thereby preventing Earth's oceans from slowly freezing solid. Without this property of water the oceans could have frozen solid during the Snowball Earth episodes. The Snowball Earth Hypothesis as it was originally proposed]] Evidence The Snowball Earth hypothesis was originally devised to explain the apparent presence of Additionally, the Van der Waals forces between water molecules give it an ability to store energy with evaporation, which upon condensation is released. The Van der Waals equation is an Equation of state that can be derived from a special form of the potential between a pair of molecules (hard-sphere repulsion In Thermochemistry, latent heat is the amount of Energy in the form of Heat released or absorbed by a substance during a change of phase Evaporation is the process by which Molecules in a Liquid state (e Condensation is the change of the physical state of aggregation (or simply state of matter from gaseous phase into liquid phase This helps moderate climate, cooling the tropics and warming the poles, helping to maintain a thermodynamic stability needed for life.

Carbon is fundamental to terrestrial life for its immense flexibility in creating covalent chemical bonds with a variety of non-metallic elements, principally nitrogen, oxygen and hydrogen. Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Carbon dioxide and water together enable the storage of solar energy in sugars, such as glucose. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Sugar is a class of edible Crystalline substances mainly Sucrose, Lactose, and Fructose. Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. The oxidation of glucose releases biochemical energy needed to fuel all other biochemical reactions. Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state

The ability to form organic acids (–COOH) and amine bases (–NH₂) gives it the possibility of neutralisation dehydrating reactions to build long polymer peptides and catalytic proteins from monomer amino acids, and with phosphates to build not only DNA, the information storing molecule of inheritance, but also adenosine triphosphate (ATP) the principal energy "currency" of cellular life. An organic acid is an Organic compound with Acidic properties Amines are Organic compounds and Functional groups that contain a basic Nitrogen Atom with a Lone pair. A polymer is a large Molecule ( Macromolecule) composed of repeating Structural units typically connected by Covalent Chemical bonds Peptides (from the Greek πεπτίδια, "small digestibles" are short Polymers formed from the linking in a defined order of α- Amino Catalysis is the process in which the rate of a Chemical reaction is increased by means of a Chemical substance known as a catalyst Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl A monomer (from Greek mono "one" and meros "part" is a small Molecule that may become chemically bonded to other In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this A phosphate, an Inorganic chemical, is a salt of Phosphoric acid. Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known Adenosine-5'-triphosphate ( ATP) is a multifunctional Nucleotide that is most important as a " molecular currency" of intracellular Energy

Due to their relative abundance and usefulness in sustaining life, many have hypothesized that life forms elsewhere in the universe would also utilize these basic materials. However, other elements and solvents could also provide a basis for life. Life is a state that distinguishes Organisms from non-living objects such as non-life and dead organisms being manifested by growth through Metabolism Silicon is most often deemed to be the probable alternative to carbon. Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 Silicon lifeforms are proposed to have a crystalline morphology, and are theorized to be able to exist in high temperatures, such as on planets which are very close to their star. Alternative biochemistry is the speculative Biochemistry of alien Life forms that differ radically from those on Earth. Life forms based in ammonia rather than water have also been suggested, though this solution appears less optimal than water. Ammonia is a compound with the formula N[[hydrogen H3]] It is normally encountered as a Gas with a characteristic pungent Odor ^[4]

Indeed, technically life is little more than any self-replicating reaction, which could arise in a great many conditions and with various ingredients, though carbon-oxygen within the liquid temperature range of water seems most conducive. Suggestions have even been made that self-replicating reactions of some sort could occur within the plasma of a star, though it would be highly unconventional. In Physics and Chemistry, plasma is an Ionized Gas, in which a certain proportion of Electrons are free rather than being bound

Several pre-conceived ideas about the characteristics of life outside of Earth have been questioned. For example, NASA scientists believe that the color of photosynthesizing pigments on extrasolar planets could be non-green. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program An extrasolar planet, or exoplanet, is a Planet beyond the Solar System, orbiting around other Stars As of September 2008 312 ^[5]

Evolution and morphology

In addition to the biochemical basis of extraterrestrial life, many have also considered evolution and morphology. eVolution is the third Album by eLDee, it was due to be released in 2008 Comparative anatomy is the study of similarities and differences in the Anatomy of Organisms It is closely related to Evolutionary biology and Phylogeny Science fiction has often depicted extraterrestrial life with humanoid and/or reptilian forms. The term " humanoid " refers to any being whose body structure resembles that of a Human. Reptiles, or members of the class Reptilia are air-breathing Cold-blooded Vertebrates that have skin covered in scales as opposed to hair or feathers Aliens have often been depicted as having light green or grey skin, with a large head, as well as four limbs—i. e. , this depiction is fundamentally humanoid. Other subjects such as felines and insects have also occurred in fictional representations of aliens. WikipediaManual of Style (spelling, articles should conform to one overall spelling style of English typically the one most linked to the article topic (if it is geographic Insects ( Class Insecta) are a major group of Arthropods and the most diverse group of Animals on the Earth with over a million described

A division has been suggested between universal and parochial (narrowly restricted) characteristics. Evolving the Alien The Science of Extraterrestrial Life (2002 published in the US and UK second edition as What Does a Martian Look Like? The Science of Extraterrestrial Universals are features which have evolved independently more than once on Earth (and thus presumably are not difficult to develop) and are so intrinsically useful that species will inevitably tend towards them. These include flight, sight, photosynthesis and limbs, all of which have evolved several times here on Earth. Flight is the process by which an object achieves sustained movement either through the Air (or movement beyond Earth's atmosphere, in the case of Photosynthesis is a Metabolic pathway that converts Light Energy into Chemical energy. A limb (from the Old English lim) is a jointed or Prehensile (as Octopus tentacles or new world Monkey tails Appendage of the There is a huge variety of eyes, for example, and many of these have radically different working schematics and different visual foci: the visual spectrum, infrared, polarity and echolocation. Eyes are organs that detect Light, and send signals along the Optic nerve to the visual areas of the brain Infrared ( IR) radiation is Electromagnetic radiation whose Wavelength is longer than that of Visible light, but shorter than that of Polarization ( ''Brit'' polarisation) is a property of Waves that describes the orientation of their oscillations Acoustic location is the art and science of using Sound to determine the distance and direction of something Parochials, however, are essentially arbitrary evolutionary forms. These often have little inherent utility (or at least have a function which can be equally served by dissimilar morphology) and probably will not be replicated. A classic example of a parochial is the curious and often fatal conjunction of the feeding and breathing passages found within many animals, although it is possible this conjunction allowed for the evolution of human speech. eVolution is the third Album by eLDee, it was due to be released in 2008 Speech refers to the processes associated with the production and perception of Sounds used in Spoken language. Intelligent aliens could communicate through gestures as deaf humans do.

Attempting to define parochial features challenges many taken-for-granted notions about morphological necessity. Skeletons, which are essential to large terrestrial organisms according to the experts of the field of Gravitational biology, are almost assuredly to be replicated elsewhere in one form or another. In Biology, the skeleton is a strong and often a rigid framework that supports the body of an animal holding it upright and giving it shape and strength (Also skeletal Gravitational Biology is the study of the effects Gravity has on living organisms. Many also conjecture as to some type of egg laying amongst extraterrestrial creatures but mammalian mammary glands might be a singular case. Mammary glands are the organs that in Mammals produce Milk for the sustenance of the young

The assumption of radical diversity amongst putative extraterrestrials is by no means settled. While many exobiologists do stress that the enormously heterogeneous nature of Earth life foregrounds even greater variety in space, others point out that convergent evolution may dictate substantial similarities between Earth and off-Earth life. Convergent evolution describes the acquisition of the same biological trait in unrelated lineages These two schools of thought are called "divergionism" and "convergionism", respectively. ^[6]

Beliefs in extraterrestrial life

Ancient and early modern ideas

See also: Cosmic pluralism

Belief in extraterrestrial life may have been present in ancient India, Egypt, Arabia, China, Babylon, Assyria and Sumer, although in these societies, cosmology was fundamentally supernatural and the notion of alien life is difficult to distinguish from that of gods, demons, and such. Cosmic pluralism, the plurality of worlds, or simply pluralism, describes the belief in numerous other worlds which harbour extraterrestrial life. India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country This article is about the country of Egypt For a topic outline on this subject see List of basic Egypt topics. The Arabian Peninsula (in Arabic: شبه الجزيرة العربية šibh al-jazīra al-ʻarabīya or جزيرة العرب jazīrat al-ʻarab) China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National Babylon was a City-state of ancient Mesopotamia, the remains of which can be found in present-day Al Hillah, Babil Province, Iraq Early history The most Neolithic site in Assyria is at Tell Hassuna, the center of the Hassuna culture Sumer ( Sumerian: sux-Latn [[Ki (earth ki]]-[[EN (cuneiform en]]-'''ĝir15''', Akkadian: Šumeru; possibly Biblical Shinar Cosmology (from Greek grc κοσμολογία - grc κόσμος kosmos, "universe" and grc -λογία -logia) is study The term supernatural or supranatural ( Latin: super, supra "above" + natura "nature" pertains to entities events The first important Western thinkers to argue systematically for a universe full of other planets and, therefore, possible extraterrestrial life were the ancient Greek writer Thales and his student Anaximander in the 7th and 6th centuries B. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly Thales of Miletus According to Bertrand Russell, "Philosophy begins with Thales Anaximander ( Ancient Greek:) (c 610 BC–c 546 BC was a Pre-Socratic Greek philosopher who lived in Miletus C. The atomists of Greece took up the idea, arguing that an infinite universe ought to have an infinity of populated worlds. In Natural philosophy, atomism is the theory that all the objects in the universe are composed of very small indestructible building blocks - Atoms Or stated in Ancient Greek cosmology worked against the idea of extraterrestrial life in one critical respect, however: the geocentric universe. In Astronomy, the geocentric model of the Universe is the superseded theory that the Earth is the center of the universe and other Championed by Aristotle and codified by Ptolemy, it favored the Earth and Earth-life (Aristotle denied there could be a plurality of worlds) and seemingly rendered extraterrestrial life philosophically untenable. Aristotle (Greek Aristotélēs) (384 BC – 322 BC was a Greek philosopher a student of Plato and teacher of Alexander the Great. Claudius Ptolemaeus ( Greek: Klaúdios Ptolemaîos; after 83 &ndash ca Lucian in his novels described inhabitants of the Moon and other celestial bodies as humanoids, but with significant differences from humans. Lucian of Samosata (Λουκιανός ὁ Σαμοσατεύς Lucianus c

Authors of Jewish sources also considered extraterrestrial life. PLEASE TAKE NOTE************ The Talmud states that there are at least 18,000 other worlds, but provides little elaboration on the nature of the worlds and on whether they are physical or spiritual. The Talmud ( Hebrew: he תַּלְמוּד is a record of Rabbinic discussions pertaining to Jewish law, ethics, customs and history Based on this, however, the 18th century exposition "Sefer HaB'rit" posits that extraterrestrial creatures exist but that they have no free will (and are thus equivalent to animal life). The question of free will It adds that human beings should not expect creatures from another world to resemble earthly life, any more than sea creatures resemble land animals. ^[7][8]

Hindu beliefs of endlessly repeated cycles of life have led to descriptions of multiple worlds in existence and their mutual contacts ( Sanskrit word Sampark (समपर्क) means 'contact' as in Mahasamparka (मह‌समपर्क) = the great contact). A Hindu ( Devanagari: हिन्दू is an adherent of the philosophies and scriptures of Hinduism, a set of religious, Philosophical Sanskrit (sa संस्कृता वाक् saṃskṛtā vāk, for short sa संस्कृतम् saṃskṛtam) is a historical According to Hindu scriptures there are innumerable universes created by the Supreme Personality of Godhead to facilitate the fulfillment of the separated desires of innumerable living entities. However, the purpose of such creations is to bring back the deluded souls to correct understanding about the purpose of life. Apart from the innumerable universes which are material, there is also the existence of unlimited spiritual world, where the purified living entities live with perfect conception about life and ultimate reality. The life of these purified beings is centered around loving devotional services to Supreme Personality of Godhead. The spiritually aspiring saints and devotees as well as thoughtful men of material world have been getting guidance and help from these purified living entities of spiritual world from time immemorial. However, the relevance of such descriptions has to be evaluated in the context of a correct understanding of geography and science at those times. Science (from the Latin scientia, meaning " Knowledge " or "knowing" is the effort to discover, and increase human understanding

Within Islam, the statement of the Qur'an "All praise belongs to God, Lord of all the worlds" indicates multiple universal bodies and maybe even multiple universes that may indicate extraterrestrial and even extradimensional life. For other meanings including people named 'Islam' see Islam (disambiguation. The Qur’an ( القرآن, literally "the recitation" also sometimes transliterated as Qur’ān, Koran, Alcoran God is the principal or sole Deity in Religions and other belief systems that worship one deity. Surat Al-Jinn also mentioned a statement from a Jinn regarding the current status and ability of his group in the heavens. Surat Al-Jinn (سورة الجن ( The Jinn or The Sprites) is the 72nd Sura of the Qur'an with 28 Ayat. GEnie (General Electric Network for Information Exchange was an online service

In the Qadiani faith, a more direct reference from the Quran is presented by Mirza Tahir Ahmad as a proof that life on other planets may exist according to Quran. The Ahmadiyya Muslim Community ( Arabic: الجماعة الأحمدية; transliterated: al-Jamā'a al-Ahmadīya) is the larger community of Mirza Tahir Ahmad (Born 18 December 1928 in Qadian, died 19 April 2003 in London) was Khalifatul Masih IV In his book, Revelation, Rationality, Knowledge & Truth, he quotes verse 42:29 "And among His Signs is the creation of the heavens and the earth, and of whatever living creatures (da'bbah) He has spread forth in both. Revelation Rationality Knowledge & Truth is a book written by Mirza Tahir Ahmad, the fourth leader of . . "; according to this verse there is life in heavens. According to the same verse "And He has the power to gather them together (jam-'i-him) when He will so please"; indicates the bringing together the life on Earth and the life elsewhere in the universe. The verse does not specify the time or the place of this meeting but rather states that this event will most certainly come to pass whenever God so desires. It should be pointed out that the Arabic term Jam-i-him used to express the gathering event can imply either a physical encounter or a contact through communication. ^[9]

When Christianity spread throughout the West, the Ptolemaic system became very widely accepted, and although the Church never issued any formal pronouncement on the question of alien life^[10] at least tacitly the idea was aberrant. Christianity ( Greek Χριστιανισμός from the word Xριστός ( Christ)is a monotheistic Religion centered on the life and teachings In 1277 the Bishop of Paris, Étienne Tempier, did overturn Aristotle on one point: God could have created more than one world (given His omnipotence) yet we know by revelation He only made one. Étienne (Stephen Tempier (also known as Stephanus of Orleans) (died September 3 1279 was a French Bishop of Paris during the thirteenth century Taking a further step and arguing that aliens actually existed remained rare. Notably, Cardinal Nicholas of Cusa speculated about aliens on the moon and sun. The Sun (Sol is the Star at the center of the Solar System.

Giordano Bruno, De l'Infinito, Universo e Mondi, 1584

There was a dramatic shift in thinking initiated by the invention of the telescope and the Copernican assault on geocentric cosmology. Giordano Bruno (1548 – February 17, 1600) was an Italian Philosopher best-known as an early proponent of Heliocentrism and A telescope is an instrument designed for the observation of remote objects and the collection of Electromagnetic radiation. Once it became clear that the Earth was merely one planet amongst countless bodies in the universe the extraterrestrial idea moved towards the scientific mainstream. God's omnipotence, it could be argued, not only allowed for other worlds and other life, on some level it necessitated them. The best known early-modern proponent of such ideas was Giordano Bruno, who argued in the 16th century for an infinite universe in which every star is surrounded by its own solar system; he was eventually burned at the stake by the Catholic church for his heretical ideas. Giordano Bruno (1548 – February 17, 1600) was an Italian Philosopher best-known as an early proponent of Heliocentrism and The Catholic church under John Paul II apologized for this. In the early 17th century the Czech astronomer Anton Maria Schyrleus of Rheita mused that "if Jupiter has…inhabitants…they must be larger and more beautiful than the inhabitants of the Earth, in proportion to the [characteristics] of the two spheres. Anton (or Antonius) Maria Schyrleus (also Schyrl, Schyrle) of Rheita (1597-1660 ( Antonín Maria Šírek z Reity) "^[11] Dominican monk Tommaso Campanella wrote about a Solarian alien race in his Civitas Solis. Tommaso Campanella ( September 5, 1568 &ndash May 21, 1639) baptized Giovanni Domenico Campanella, was an Italian The City of the Sun (La città del Sole Latin: Civitas Solis) is a philosophical work by the Italian Dominican philosopher Tommaso Campanella

Such comparisons also appeared in poetry of the era. In "The Creation: a Philosophical Poem in Seven Books" (1712) Sir Richard Blackmore observed: "We may pronounce each orb sustains a race / Of living things adapted to the place". Sir Richard Blackmore, ( 22 January 1654 &ndash 9 October 1729) English Poet and Physician, is remembered primarily The didactic poet Henry More took up the classical theme of the Greek Democritus in "Democritus Platonissans, or an Essay Upon the Infinity of Worlds" (1647). Henry More ( October 12 1614 &ndash September 1, 1687) was an English Philosopher of the Cambridge Platonist school Democritus ( Greek:) was a pre-Socratic Greek Materialist Philosopher (born at Abdera in Thrace ca With the new relative viewpoint that the Copernican revolution had wrought, he suggested "our world's sunne / Becomes a starre elsewhere. " Fontanelle's "Conversations on the Plurality of Worlds" (translated into English in 1686) offered similar excursions on the possibility of extraterrestrial life, expanding rather than denying the creative sphere of a Maker. Bernard le Bovier de Fontenelle, also referred to as Bernard le Bouyer de Fontenelle ( 11 February 1657 &ndash 9 January 1757) was

The possibility of extraterrestrials remained a widespread speculation as scientific discovery accelerated. William Herschel, the discoverer of Uranus, was one of many 18th-19th century astronomers convinced that our Solar System, and perhaps others, would be well populated by alien life. Sir Frederick William Herschel FRS KH ( 15 November 1738 – 25 August 1822) was a German -born British Other luminaries of the period who championed "cosmic pluralism" included Immanuel Kant and Benjamin Franklin. Immanuel Kant (ɪmanuəl kant 22 April 1724 12 February 1804 was an 18th-century German Philosopher from the Prussian city of Königsberg Benjamin Franklin ( April 17 1790 was one of the Founding Fathers of the United States of America. At the height of the Enlightenment even the Sun and Moon were considered candidates for extraterrestrial inhabitants. The Age of Enlightenment or The Enlightenment is a term used to describe a phase in Western philosophy and cultural life centered upon the eighteenth century The Sun (Sol is the Star at the center of the Solar System.

Extraterrestrials and the modern era

The Arecibo message is a digital message sent to globular star cluster M13, and is a well-known symbol of human attempts to contact extraterrestrials. The Arecibo message was beamed via frequency modulated Radio waves into space at a ceremony to mark the remodeling of the Arecibo radio telescope The Great Globular Cluster in Hercules (also known as the Hercules Globular Cluster, Messier Object 13, Messier 13, M13, or NGC 6205

This enthusiasm toward the possibility of alien life continued well into the 20th century. Indeed, the roughly three centuries from the Scientific Revolution through the beginning of the modern era of solar system probes were essentially the zenith for belief in extraterrestrials in the West. The period which many historians of science call the Scientific Revolution can be roughly dated as having begun in 1543 the year in which Nicolaus Copernicus published The Solar System consists of the Sun and those celestial objects bound to it by Gravity. Many astronomers and other secular thinkers, at least some religious thinkers, and much of the general public were largely satisfied that aliens were a reality. This trend was finally tempered as actual probes visited potential alien abodes in the solar system. The moon was decisively ruled out as a possibility while Venus and Mars, long the two main candidates for extraterrestrials, showed no obvious evidence of current life. The VENUS ( V ictoria E xperimental N etwork U nder the S ea project is a cabled sea floor observatory operated by the University The other large moons of our system which have been visited appear similarly lifeless, though the interesting geothermic forces observed (Io's volcanism, Europa's ocean, Titan's thick atmosphere) have underscored how broad the range of potentially habitable environments may be. TemplateInfobox Planet.--> Io (ˈaɪoʊ, or as Greek TemplateInfobox Planet.--> Europa (jʊˈroʊpə; or as TemplateInfobox Planet.--> Titan (ˈtaɪtən, or as Although the hypothesis of a deliberate cosmic silence of advanced extraterrestrials is also a possibility,^[12] the failure of the SETI program to detect anything resembling an intelligent radio signal after four decades of effort has partially dimmed the optimism that prevailed at the beginning of the space age. Search for Extra-Terrestrial Intelligence ( SETI) is the collective name for a number of activities to detect intelligent Extraterrestrial life. Emboldened critics view the search for extraterrestrials as unscientific, despite the fact the SETI program is not the result of a continuous, dedicated search but instead utilizes what resources and manpower it can, when it can. Search for Extra-Terrestrial Intelligence ( SETI) is the collective name for a number of activities to detect intelligent Extraterrestrial life. ^[13]

Thus, the three decades preceding the turn of the second millennium saw a crossroads reached in beliefs in alien life. The prospect of ubiquitous, intelligent, space-faring civilizations in our solar system appears increasingly dubious to many scientists. Still, in the words of SETI's Frank Drake, "All we know for sure is that the sky is not littered with powerful microwave transmitters. Dr Frank Donald Drake (born May 28 1930, Chicago) is an American Astronomer and Astrophysicist. "^[14] Drake has also noted that it is entirely possible advanced technology results in communication being carried out in some way other than conventional radio transmission. At the same time, the data returned by space probes and giant strides in detection methods have allowed science to begin delineating habitability criteria on other worlds and to confirm that, at least, other planets are plentiful though aliens remain a question mark. Planetary habitability is the measure of a Planet 's or a Natural satellite 's potential to develop and sustain Life. An extrasolar planet, or exoplanet, is a Planet beyond the Solar System, orbiting around other Stars As of September 2008 312

In 2000, geologist and paleontologist Peter Ward and astrobiologist Donald Brownlee published a book entitled Rare Earth: Why Complex Life is Uncommon in the Universe. A geologist is a contributor to the Science of Geology, studying the physical structure and processes of the Earth and planets of the solar system Palaeontology redirects here For the Scientific journal, see Palaeontology (journal. Peter Ward may refer to Peter Ward (English footballer (born 1955 retired English footballer played for Brighton & Hove Albion and Nottingham Forest Astrobiology (from Greek grc ἄστρον astron, "constellation star" grc βίος bios, "life" and grc -λογία ^[15] In it, they discussed the Rare Earth hypothesis, in which they claim that Earth-like life is rare in the universe, while microbial life is common in the universe. In Planetary astronomy and Astrobiology, the Rare Earth hypothesis argues that the emergence of complex Multicellular life ( Metazoa EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 The Universe is defined as everything that Physically Exists: the entirety of Space and Time, all forms of Matter, Energy The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have

The possible existence of primitive (microbial) life outside of Earth is much less controversial to mainstream scientists although at present no direct evidence of such life has been found. Indirect evidence has been offered for the current existence of primitive life on the planet Mars. However, the conclusions that should be drawn from such evidence remain in debate.

Scientific search for extraterrestrial life

The scientific search for extraterrestrial life is being carried out in two different ways, directly and indirectly.

Direct search

The planned NASA Kepler mission for the search of extrasolar planets. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program The Kepler Mission is a Space Photometer being developed by NASA. An extrasolar planet, or exoplanet, is a Planet beyond the Solar System, orbiting around other Stars As of September 2008 312

Scientists are directly searching for evidence of unicellular life within the solar system, carrying out studies on the surface of Mars and examining meteors that have fallen to Earth. The Solar System consists of the Sun and those celestial objects bound to it by Gravity. A mission is also proposed to Europa, one of Jupiter's moons with a possible liquid water layer under its surface, which might contain life. TemplateInfobox Planet.--> Europa (jʊˈroʊpə; or as

There is some limited evidence that microbial life might possibly exist or have existed on Mars. ^[16] An experiment on the Viking Mars lander reported gas emissions from heated Martian soil that some argue are consistent with the presence of microbes. NASA 's Viking program consisted of a pair of space probes sent to Mars, Viking 1 and Viking 2. However, the lack of corroborating evidence from other experiments on the Viking indicates that a non-biological reaction is a more likely hypothesis. Recently, Circadian rhythms have been allegedly discovered in Viking data. The interpretation is controversial, see Viking biological experiments. The two Viking spacecraft each carried four types of Biological Experiments to the surface of Mars in the late 1970s Independently in 1996 structures resembling nanobacteria were reportedly discovered in a meteorite, ALH84001, thought to be formed of rock ejected from Mars. Nanobacteria is the name of a possible class of living organisms specifically cell-walled Microorganisms with a size much smaller than the generally accepted ALH 84001 (full name Allan Hills 84001) is a Meteorite found in Allan Hills, Antarctica in December 1984 by a team of US meteorite hunters from A Mars meteorite is a Meteorite that has landed on Earth and originated from Mars. This report is also controversial and scientific debate continues.

In February 2005, NASA scientists reported that they had found strong evidence of present life on Mars. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program ^[17] The two scientists, Carol Stoker and Larry Lemke of NASA's Ames Research Center, based their claims on methane signatures found in Mars' atmosphere that resemble the methane production of some forms of primitive life on Earth, as well as their own study of primitive life near the Rio Tinto river in Spain. NASA Ames Research Center (ARC is a NASA facility located at Moffett Federal Airfield, which covers 43 acres at the borders of the cities of Mountain View The Río Tinto is a River in southwestern Spain that originates in the Sierra Morena mountains of Andalusia. Spain () or the Kingdom of Spain (Reino de España is a country located mostly in southwestern Europe on the Iberian Peninsula. NASA officials soon denied the scientists' claims, and Stoker herself backed off from her initial assertions. ^[18]

Though such findings are still very much in debate, support among scientists for the belief in the existence of life on Mars seems to be growing. In an informal survey conducted at the conference in which the European Space Agency presented its findings, 75 percent of the scientists in attendance reported to believe that life once existed on Mars; 25 percent reported a belief that life currently exists there. The European Space Agency ( ESA) established in 1975 is an intergovernmental organisation dedicated to the exploration of space, currently with 17 member ^[19]

The Gaia hypothesis stipulates that any planet with a robust population of life will have an atmosphere that is not in chemical equilibrium, which is relatively easy to determine from a distance by spectroscopy. The Gaia hypothesis is an ecological Hypothesis proposing that the Biosphere and the physical components of the Earth ( Atmosphere Spectroscopy was originally the study of the interaction between Radiation and Matter as a function of Wavelength (λ However, significant advances in the ability to find and resolve light from smaller rocky worlds near to their star are necessary before this can be used to analyze extrasolar planets

Indirect search

Terrestrial Planet Finder - A planned Infrared interferometer for finding Earth-like extrasolar planets (as of 2007 , it has not received the funding from NASA it needs — that funding is going towards the Kepler mission). An extrasolar planet, or exoplanet, is a Planet beyond the Solar System, orbiting around other Stars As of September 2008 312 The Terrestrial Planet Finder ( TPF) was a plan by the National Aeronautics and Space Administration of the United States for a Telescope An extrasolar planet, or exoplanet, is a Planet beyond the Solar System, orbiting around other Stars As of September 2008 312 The Kepler Mission is a Space Photometer being developed by NASA.

It is theorised that any technological society in space will be transmitting information. Projects such as SETI are conducting an astronomical search for radio activity that would confirm the presence of intelligent life. Search for Extra-Terrestrial Intelligence ( SETI) is the collective name for a number of activities to detect intelligent Extraterrestrial life. A related suggestion is that aliens might broadcast pulsed and continuous laser signals in the optical as well as infrared spectrum;^[20] laser signals have the advantage of not "smearing" in the interstellar medium and may prove more conducive to communication between the stars. A laser is a device that emits Light ( Electromagnetic radiation) through a process called Stimulated emission. And while other communication techniques including laser transmission and interstellar spaceflight have been discussed seriously and may not be infeasible, the measure of effectiveness is the amount of information communicated per unit cost, resulting with the radio as method of choice.

Extrasolar planets

Astronomers also search for extrasolar planets that they believe would be conducive to life, such as Gliese 581 c and OGLE-2005-BLG-390Lb, which have been found to have Earth-like qualities. An extrasolar planet, or exoplanet, is a Planet beyond the Solar System, orbiting around other Stars As of September 2008 312 Gliese 581 c (ˈgliːzə is a " Super-earth " ^[21][22] Current radiodetection methods have been inadequate for such a search, as the resolution afforded by recent technology is inadequate for detailed study of extrasolar planetary objects. Future telescopes should be able to image planets around nearby stars, which may reveal the presence of life (either directly or through spectrography which would reveal key information such as the presence of free oxygen in a planet's atmosphere):

Artist's Impression of Gliese 581 c, the first extrasolar planet discovered within its star's habitable zone. In Analytical chemistry, atomic absorption spectroscopy is a technique for determining the concentration of a particular metal element in a sample Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Gliese 581 c (ˈgliːzə is a " Super-earth " An extrasolar planet, or exoplanet, is a Planet beyond the Solar System, orbiting around other Stars As of September 2008 312 In Astronomy a habitable zone ( HZ) is a region of space where conditions are favorable for Life as it may be found on Earth.

• Darwin is an ESA mission designed to find Earth-like planets, and analyse their atmosphere. The Darwin Mission is a proposed European Space Agency (ESA program designed to directly detect Earth -like planets orbiting nearby stars, and search for
• The COROT mission, initiated by the French Space Agency, was launched in 2006 and is currently looking for extrasolar planets -- it is the first of its kind
• The Terrestrial Planet Finder was supposed to be launched by NASA, but as of 2007 , budget cuts have caused it to be delayed indefinitely
• The Kepler Mission, largely replacing the Terrestrial Planet Finder, to be launched in November 2008

It has been argued that Alpha Centauri, the closest star system to Earth, may contain planets which could be capable of sustaining life. COROT ( CO nvection RO tation and planetary T ransits is a space mission led by the French Space Agency (CNES in conjunction with the European The fr '''Centre National d'Études Spatiales''' ( CNES) is the French government Space agency (administratively a "public establishment of industrial and commercial The Terrestrial Planet Finder ( TPF) was a plan by the National Aeronautics and Space Administration of the United States for a Telescope The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program The Kepler Mission is a Space Photometer being developed by NASA. Alpha Centauri (α Centauri / α Cen also known as Rigil Kentaurus, Rigil Kent, or Toliman, is the brightest Star in the southern Constellation ^[23]

On April 24, 2007, scientists at the European Southern Observatory in La Silla, Chile said they had found the first Earth-like planet. Events 1479 BC - Thutmose III ascends to the throne of Egypt, although power effectively shifts to Hatshepsut (according to Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. The planet, known as Gliese 581 c, orbits within the habitable zone of its star Gliese 581, a red dwarf star which is a scant 20. Gliese 581 c (ˈgliːzə is a " Super-earth " In Astronomy a habitable zone ( HZ) is a region of space where conditions are favorable for Life as it may be found on Earth. Gliese 581 (ˈgliːzə is a Red dwarf Star with spectral type M3V located 20 According to the Hertzsprung-Russell diagram, a red dwarf star is a small and relatively cool Star, of the Main sequence, either late K 5 light years (194 trillion km) from Earth. A light-year or light year (symbol ly) is a unit of Length, equal to just under ten trillion Kilometres As defined by It was initially thought that this planet could contain liquid water. However, recent computer simulations of the climate on Gliese 581c by Werner Von Bloh and his team at Germany's Institute for Climate Impact Research suggest carbon dioxide and methane in the atmosphere would create a runaway greenhouse effect. This would warm the planet well above the boiling point of water (100 degrees Celsius/212 degrees Fahrenheit), thus dimming the hopes of finding life. As a result of greenhouse models, scientists are now turning their attention to Gliese 581 d, which lies just outside of the star's traditional habitable zone. Gliese 581 d (ˈgliːzə is an Extrasolar planet approximately 20 Light-years away in the Constellation of Libra. ^[24]

On May 29, 2007, the Associated Press released a report stating that scientists have identified twenty-eight exo-solar planetary bodies. Events 363 - Roman Emperor Julian defeats the Sassanid army in the Battle of Ctesiphon, under the walls of the Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. One of these newly discovered planets is said to have many similarities with Neptune. ^[25]

Drake equation

Main article: Drake equation

In 1961, University of California, Santa Cruz astronomer and astrophysicist Dr. The Drake equation (also sometimes called the "Green Bank equation" the "Green Bank Formula" or often erroneously labeled the " Sagan equation" Historically Astronomy was more concerned with the classification and description of phenomena in the sky while Astrophysics attempted to explain these phenomena Frank Drake devised the Drake equation, which mathematically simplifies 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, and the fraction of possible communicative planets, and the "lifetime" of possible communicative civilizations which scientifically stated there are an estimated 10,000 planets containing intelligent life with the possible capability of communicating with Earth in the Milky Way galaxy. Dr Frank Donald Drake (born May 28 1930, Chicago) is an American Astronomer and Astrophysicist. The Drake equation (also sometimes called the "Green Bank equation" the "Green Bank Formula" or often erroneously labeled the " Sagan equation" EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 The Milky Way (a translation of the Latin Via Lactea, in turn derived from the Greek Γαλαξίας (Galaxias sometimes referred to simply ^[26]

Extraterrestrial life in the Solar System

This planetary habitability chart shows where life might exist on extrasolar planets based on our own Solar System and life on Earth. Planetary habitability is the measure of a Planet 's or a Natural satellite 's potential to develop and sustain Life. The Solar System consists of the Sun and those celestial objects bound to it by Gravity. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001

Europa, due to the ocean under its icy crust, might host some form of microbial life.^[27][2]

Many bodies in the Solar System have been suggested as being capable of containing conventional organic life. TemplateInfobox Planet.--> Europa (jʊˈroʊpə; or as The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have The most commonly suggested ones are listed below; of these, five of the nine are moons, and are thought to have large bodies of underground liquid (streams), where life may have evolved in a similar fashion to deep sea vents.

• Mars - Life on Mars has been long speculated. Scientists have long speculated about the possibility of life on Mars owing to the planet's proximity and similarity to Earth. Liquid water is widely thought to have existed on Mars in the past and there may still be liquid water beneath the surface. Methane was found in the atmosphere of Mars. Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. Recent photographs from Mars Global Surveyor show evidence of recent (within 10 years) flows of a liquid on the Red Planet's frigid surface. The Mars Global Surveyor ( MGS) was a US Spacecraft developed by NASA and the Jet Propulsion Laboratory and launched ^[28]
• Europa - Europa may contain liquid water beneath its 100-mile (160 km) thick ice layer. TemplateInfobox Planet.--> Europa (jʊˈroʊpə; or as Vents on the bottom of the ocean warm the ice so that 60 miles (97 km) of liquid could exist beneath the ice layer, perhaps capable of supporting microbes and simple plants. A microorganism (also spelled micro organism or micro-organism and also called a microbe) is an Organism that is Microscopic (usually Plants are living Organisms belonging to the kingdom Plantae. ^[2]
• Jupiter - Possible supporter of floating animals, as hypothesized by Carl Sagan for gas giants in general. Carl Edward Sagan ( November 9 1934 &ndash December 20 1996) was an American Astronomer, astrochemist, author This point of view is somewhat controversial because these creatures would not be water-based, but ammonia-based. Ammonia is a compound with the formula N[[hydrogen H3]] It is normally encountered as a Gas with a characteristic pungent Odor ^[29]
• Ganymede - Possible underground ocean (see Europa). TemplateInfobox Planet.--> Ganymede (ˈgænɨmiːd, or as Greek TemplateInfobox Planet.--> Europa (jʊˈroʊpə; or as
• Callisto - Possible underground ocean (see Europa). TemplateInfobox Planet.--> Callisto (kəˈlɪstoʊ, or as Greek TemplateInfobox Planet.--> Europa (jʊˈroʊpə; or as
• Saturn - Possible floating creatures (see Jupiter).
• Enceladus - Geothermal activity, watervapour. TemplateInfobox Planet.--> This article is about the moon of Possible underice oceans heated by tidal effects.
• Titan (Saturn's largest moon) - The only known moon with a significant atmosphere was recently visited by the Huygens probe. TemplateInfobox Planet.--> Titan (ˈtaɪtən, or as The Huygens probe, supplied by the European Space Agency (ESA and named after the Dutch 17th century astronomer Christiaan Huygens, is an atmospheric entry Latest discoveries indicate that there is no global or widespread ocean, but small and/or seasonal liquid hydrocarbon lakes are present on the surface (the first liquid lakes discovered outside of Earth). In Organic chemistry, a hydrocarbon is an Organic compound consisting entirely of Hydrogen and Carbon. A lake (from Latin lacus) is a Terrain feature (or Physical feature) a body of Liquid on the surface of a world that is localized to the ^[30][31][32]
• Venus - Recently, scientists have speculated the existence of microbes in the stable cloud layers 50 km above the surface, evidenced by hospitable climates and chemical disequilibrium. The VENUS ( V ictoria E xperimental N etwork U nder the S ea project is a cabled sea floor observatory operated by the University ^[33]

Numerous other bodies have been suggested as potential hosts for microbial life. The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have Fred Hoyle has proposed that life might exist on comets, as some Earth microbes managed to survive on a lunar probe for many years. Sir Fred Hoyle FRS ( 24 June, 1915  &ndash 20 August, 2001) was an English Astronomer primarily However, it is considered highly unlikely that complex multicellular organisms of the conventional chemistry of terrestrial life (animals, plants) could exist under these living conditions.

See also

Events and objects

• ALH84001 - a Mars meteorite with disputed microbial formations
• Gliese 581 c
• Gliese 581 d
• Red rain in Kerala
• Wow! signal

Searches for extraterrestrial life

• Communication with Extraterrestrial Intelligence
• Darwin - an ESA mission designed to find Earth-like planets and analyze their atmosphere for signs of life. ALH 84001 (full name Allan Hills 84001) is a Meteorite found in Allan Hills, Antarctica in December 1984 by a team of US meteorite hunters from A Mars meteorite is a Meteorite that has landed on Earth and originated from Mars. Gliese 581 c (ˈgliːzə is a " Super-earth " Gliese 581 d (ˈgliːzə is an Extrasolar planet approximately 20 Light-years away in the Constellation of Libra. WaterSamplejpg|thumb|Rain water sample (left and after the particles settled (right The Wow ! signal was a strong Narrowband radio signal detected by Dr CETI (Communication with Extraterrestrial Intelligence is a branch of SETI research that focuses on composing and deciphering messages that could theoretically be understood The Darwin Mission is a proposed European Space Agency (ESA program designed to directly detect Earth -like planets orbiting nearby stars, and search for The European Space Agency ( ESA) established in 1975 is an intergovernmental organisation dedicated to the exploration of space, currently with 17 member
• SETI (Search for Extra-Terrestrial Intelligence)
• Allen Telescope Array

Subjects

Theories

References

Further reading

External links

• 'The UFO Disclosure Project'A Demand for Congressional hearings on UFOs and related technology "Video"
• 'The truth is out there'UFOs Filmed 26 July 2007. Events 657 - Battle of Siffin. 811 - Battle of Pliska; Byzantine Emperor Nicephorus Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century.
• 'Is There Anybody Out There?' Freeview video by the Vega Science Trust and the BBC/OU.
• PBS: Life Beyond Earth a film by Timothy Ferris
• PBS: Exploring Space - The Quest for Life by Scott Pearson
• ufoskeptic.org by Bernard Haisch
• Xenopsychology by Robert A. Freitas Jr.
• "What Aliens Might Look Like" from National Geographic
• Sylvia Engdahl, "Early Space Poetry" Part I: Didactic and other poetry concerning other inhabited worlds, well-known and obscure poets, 17th-18th centuries. Overview The NGS's historical mission is "to increase and diffuse geographic knowledge while promoting the conservation of the world's cultural historical and natural "Part II": 19th century
• Top stars picked in alien search
• "Snaiad", a realistic world-design exercise by Nemo Ramjet