 The existence of extraterrestrial life remains hypothetical though human beings continue to search Extraterrestrial life is life that may exist and originate outside the planet Earth. Its existence is currently hypothetical: there is as yet no evidence of extraterrestrial life that has been widely accepted by scientists. Image File history File links Download high resolution version (2257x1736, 2787 KB)This picture of the MKII radio telescope at the Joddrell Bank Observatory, University of Manchester, is reproduced with permission. ...
Image File history File links Download high resolution version (2257x1736, 2787 KB)This picture of the MKII radio telescope at the Joddrell Bank Observatory, University of Manchester, is reproduced with permission. ...
Life is a multi-faceted concept. ...
Earth, also known as the Earth, Terra, and (mostly in the 19th century) Tellus, is the third-closest planet to the Sun. ...
Most scientists hold that if extraterrestial life exists, its evolution would have occurred independently in different places in the universe. An alternative hypothesis, held by a minority, is panspermia, which suggests that life in the universe could have stemmed from a single initial distribution of spores that provide the basis for living beings to develop. If true, this theory would suggest that life in various forms might exist throughout the universe. Panspermia is the hypothesis that the seeds of life are prevalent throughout the universe, and furthermore that life on Earth began by such seeds landing on Earth and propagating themselves. ...
Speculative forms of extraterrestrial life range from humanoid and monstrous beings seen in works of science fiction to life at the much smaller scale of bacteria and viruses. The term humanoid refers to any being whose body structure resembles that of a human. ...
Science fiction is a form of speculative fiction principally dealing with the impact of imagined science and technology, or both, upon society and persons as individuals. ...
Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ...
A virus is a microscopic parasite that infects cells in biological organisms. ...
Extraterrestrial life forms, especially intelligent ones, are often referred to in popular culture as aliens or ETs. The putative study and theorisation of ET life is known as astrobiology or xenobiology. In popular fiction and conspiracy theories, life forms, especially intelligent life forms, that are of extraterrestrial origin, i. ...
Astrobiology is an interdisciplinary field, combining aspects of astronomy, biology and geology, which considers the question of whether extraterrestrial life exists and if so, then what are its origin, distribution, and evolution. ...
Possible basis of extraterrestrial life
Biochemistry All life on Earth is based on the building block element carbon with water as the solution in which bio-chemical reactions take place. Given their relative abundance and usefulness in sustaining life it has long been assumed that life forms elsewhere in the universe will also utilize these basic components. However, other elements and solvents might be capable of providing a basis for life (Main article: Alternative biochemistry). Silicon is usually considered the most likely alternative to carbon, though this remains improbable. Life forms based in ammonia rather than water are also considered, though less frequently. Nor can the possibility be rejected that a completely new substance may be found that may react in a similar way to carbon or that wholly unique, non-chemical life-forms may possibly flourish through exotic physics. General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Atomic mass 12. ...
Water (from the Old English word wæter; c. ...
Life is a multi-faceted concept. ...
Alternative biochemistry collectively refers to an assortment of astrobiology theories and hypotheses in which life is based on chemical systems other than those used by currently known forms of life. ...
General Name, Symbol, Number silicon, Si, 14 Chemical series metalloids Group, Period, Block 14, 3, p Appearance dark gray, bluish tinge Atomic mass 28. ...
Ammonia is a compound of nitrogen and hydrogen with the formula NH3. ...
Along with a building block element and a solvent life also requires an energy source. Energy from a parent star is the most obvious source for extraterrestrial life but this is not the only possibility, as the example of terrestrial extremophiles shows. Geothermal energy from a planet's interior, for instance, may drive sub-surface or oceanic life, while tidal flexing (e.g., for bodies orbiting a gas giant) provides another possible motor to sustain living things. The Pleiades star cluster A star is a massive body of plasma in outer space that is currently producing or has produced energy through nuclear fusion. ...
An extremophile is an organism, usually unicellular, which thrives in or requires extreme conditions. ...
Earth cutaway from core to exosphere. ...
The tidal force is a secondary effect of the force of gravity and is responsible for the tides. ...
The scientific study of the possible biochemical basis for extraterrestrial life is often called xenobiology. Astrobiology is an interdisciplinary field, combining aspects of astronomy, biology and geology, which considers the question of whether extraterrestrial life exists and if so, then what are its origin, distribution, and evolution. ...
- Related topic: Back-contamination
Back-contamination is the informal but widely-employed name for the introduction of microbial extraterrestrial organisms into Earths biosphere. ...
Theoretical Evolution and Morphology Along with the biochemical basis of extraterrestrial life, there remains a broader consideration of evolution and morphology. What might an alien look like? Science fiction has long shown a bias towards humanoid or (in the case of villains) reptilian forms. The classical alien is light green or grey skinned, with an enormous head, small body, and the typical four limb and two to five digit structure—i.e., it is fundamentally humanoid with a large brain to indicate great intelligence. Other subjects from our animal mythos (felines, insects) have also featured strongly in fictional representations of aliens. While such bias is predictable, it is also curiously unimaginative and almost certain to be proven wrong should human beings encounter extraterrestrials. A phylogenetic tree of all living things, based on rRNA gene data, showing the separation of the three domains, bacteria, archaea, and eukaryotes, as described initially by Carl Woese. ...
Comparative anatomy is the study of similarities and differences in organisms. ...
Orders Crocodilia - Crocodilians scary crocodiles. ...
The Greys have landed! Alien mannequin at International UFO Museum & Research Center; Roswell, NM, USA Greys (also known as Zetas or Reticulians after the ζ Reticuli star system) are the type of intelligent extraterrestrial life that appears most commonly in modern conspiracy theories, particularly UFO conspiracy theories and other UFO-related...
Comparative brain sizes In the anatomy of animals, the brain, or encephalon (Greek for in the head), is the higher, supervisory center of the nervous system. ...
Mythos can mean: A collection of myths A web-based comic and video game series created by Variant Interactive; see Mythos: the Demon Hunters A brand of Greek beer; see Mythos (beer) A Canadian music project; see Mythos (musical project) An Origins Award-winning card game released in 1996 by...
CATS The Musical is a musical composed by Andrew Lloyd Webber (ALW) in 1981 based on Old Possums Book of Practical Cats by T. S. Eliot. ...
Orders Subclass Apterygota Symphypleona - globular springtails Subclass Archaeognatha (jumping bristletails) Subclass Dicondylia Monura - extinct Thysanura (common bristletails) Subclass Pterygota Diaphanopteroidea - extinct Palaeodictyoptera - extinct Megasecoptera - extinct Archodonata - extinct Ephemeroptera (mayflies) Odonata (dragonflies and damselflies) Infraclass Neoptera Blattodea (cockroaches) Mantodea (mantids) Isoptera (termites) Zoraptera Grylloblattodea Dermaptera (earwigs) Plecoptera (stoneflies) Orthoptera (grasshoppers, crickets...
In considering the subject more seriously, a useful division has been suggested between universal and parochial characteristics. 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 with differing materialization. There are a huge variety of eyes, for example, many of which have radically different working schematics as well as different visual foci: the visual spectrum, infrared, polarity and echolocation. Parochials, by contrast, are essentially arbitrary evolutionary forms which often serve little utility (or at least have a function which can be equally served by dissimilar morphology) and probably will not be replicated. Parochials include the five digits of mammals, the genitalia and sexual mechanics of animals, as well as the curious and often fatal conjunction of the feeding and breathing passages found within many animals. Evolving the Alien: The Science of Extraterrestrial Life (2002, second edition published as What Does a Martian Look Like? The Science of Extraterrestrial Life) is a book about xenobiology by biologist Jack Cohen and mathematician Ian Stewart. ...
Flight is the process of flying: either movement through the air by aerodynamically generating lift or aerostatically using buoyancy, or movement beyond earths atmosphere by spacecraft. ...
Visual perception is one of the senses, consisting of the ability to detect light and interpret (see) it as the perception known as sight or naked eye vision. ...
Leaf. ...
A limb (from the Old English lim) is a jointed appendage of the human or animal body; a large or main branch of a tree; a representative, branch or member of a group or organization. ...
The optical spectrum (light or visible spectrum) is the portion of the electromagnetic spectrum that is visible to the human eye. ...
Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of microwave radiation. ...
layers]] that separate organs or subcompartments in organisms. ...
See: Animal echolocation: animals emitting sound waves and listening to the echo in order to locate objects or navigate. ...
Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals primarily characterized by the presence of mammary...
A sex organ, or primary sexual characteristic, narrowly defined, is any of those parts of the body (which are not always bodily organs according to the strict definition) which are involved in sexual reproduction and constitute the reproductive system in an complex organism; namely: Male: penis (notably the glans penis...
A consideration of which features are ultimately parochial challenges many taken for granted notions about morphological necessity. Skeletons, in some form, are likely to be replicated elsewhere, yet the vertebrate spine—while a profound development on Earth—is just as likely to be unique. Similarly, it is reasonable to expect some type of egg laying amongst off-Earth creatures but the mammary glands which set apart mammals may be a singular case. Skeleton is also a winter sport: see skeleton (sport). ...
Groups Conodonta Hyperoartia Petromyzontidae (lampreys) Pteraspidomorphi (early jawless fish) Thelodonti Anaspida Cephalaspidomorphi (early jawless fish) Galeaspida Pituriaspida Osteostraci Gnathostomata (jawed vertebrates) Placodermi Chondrichthyes (cartilaginous fish) Acanthodii Osteichthyes (bony fish) Actinopterygii (ray-finned fish) Sarcopterygii (lobe-finned fish) Actinistia (coelacanths) Dipnoi (lungfish) Tetrapoda Amphibia Amniota Sauropsida/(Reptiles) Aves (Birds) Synapsida Mammalia...
Look up spine on Wiktionary, the free dictionary. ...
Mammary glands are milk-secreting adaptations of sweat glands and are the characteristic of mammals which gave the class its name. ...
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 dictates substantial similarities between Earth and off-Earth life. These two schools of thought are called "divergionism" and "convergionism", respectively [1]. In evolutionary biology, convergent evolution describes the process whereby organisms not closely related independently acquire similar characteristics while evolving in separate and sometimes varying ecosystems. ...
Beliefs in extraterrestrial life
Ancient and Early Modern ideas Belief in extraterrestrial life may have been present in ancient Egypt, Babylon, and Sumer, although in these societies, cosmology was fundamentally supernatural and the notion of aliens is difficult to distinguish from that of gods, demons, and such. The first important Western thinkers to argue systematically for a universe full of other planets and, vicariously, possible extraterrestrial life were the ancient Greek writers Thales and his student Anaximander in the 7th and 6th centuries B.C.E. The atomists of Greece took up the idea, arguing that an infinite universe ought to have an infinity of populated worlds. Ancient Greek cosmology worked against the idea of extraterrestrial life in one critical respect, however: the geocentric universe, championed by Aristotle and codified by Ptolemy, privileged the Earth and Earth-life (Aristotle denied there could be a plurality of worlds) and seemingly rendered extraterrestrial life impossible. Cosmic pluralism or the plurality of worlds describes the belief in numerous other worlds beyond the Earth which harbour extraterrestrial life. ...
Babylon is the Greek variant of Akkadian Babilu, an ancient city in Mesopotamia (Location: 32° 32′ 11″ N, 44° 25′ 15″ E, modern Al Hillah, Iraq). ...
Sumer (or Shumer, Sumeria, Egyptian Sangar, Bib. ...
Cosmology, from the Greek: κοσμολογία (cosmologia, κόσμος (cosmos) world + λογια (logia) discourse) is the study of the universe in its totality and by extension mans place in it. ...
Thales (in Greek: Θαλης) of Miletus (ca. ...
Anaximander (Greek: ΑναξίμανδÏος) (610 BC/609–c. ...
Atomism is the theory that all the objects in the universe are composed of very small particles that were not created and that will have no end. ...
The geocentric model (in Greek: geo = earth and centron = centre) of the universe is a paradigm which places the Earth at its center. ...
Aristotle, marble copy of bronze by Lysippos. ...
Claudius Ptolemaeus, given contemporary German styling, in a 16th century engraved book frontispiece. ...
When Christianity spread through the West the Ptolemaic system became dogma and although the Church never issued any formal pronouncement on the question of alien life [2], at least tacitly the idea was heretical. In 1277 the Bishop of Paris, Etienne 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. To take a further step and argue that aliens actually existed remained dangerous. The best known early-modern proponent of extra-solar planets and widespread life off Earth was Giordano Bruno, who was burned at the stake for this and other unorthodox ideas in 1600. Wikipedia does not have an article with this exact name. ...
Wikipedia does not have an article with this exact name. ...
Giordano Bruno Giordano Bruno (1548 – February 17, 1600), a. ...
History Main article: History of Christianity See also: Timeline of Christianity The history of Christianity is difficult to extricate from that of the European West (and several other culture-regions) in general. ...
The archbishop of Paris is one of twenty-three archbishops in France. ...
Giordano Bruno Giordano Bruno (1548 – February 17, 1600), a. ...
// Events January January 1 - Scotland adopts January 1st as being New Years Day February February 17 - Giordano Bruno burned at the stake for heresy in Rome July July 2 - Battle of Nieuwpoort: Dutch forces under Maurice of Nassau defeat Spanish forces under Archduke Albert in a battle on the...
The Church, however, could not contain the storm that accompanied the invention of the telescope and the Copernican assault on geocentric cosmology. 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. 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 [size] of the two spheres;" he did not dare to confirm the existence of Jovian beings due to potential theological difficulties. Later, this bold step would be taken. 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. Other luminaries of the period who championed "cosmic pluralism" included Immanuel Kant and Benjamin Franklin. At the height of the Enlightenment even the Sun and Moon were considered candidates for hosting aliens. The Christian attitude towards extraterrestrials turned from denial to ambivalence. Theological criticisms had been partially stalemated by a critical counter-argument that had remained in the background since the pronouncements of 1277: God's omnipotence not only allowed for other worlds and other life, on some level it necessitated them. 50 cm refracting telescope at Nice Observatory. ...
In astronomy, heliocentrism is the theory that the Sun is at the center of the Universe and/or the Solar System. ...
Schyrleus of Rheitas lunar map (1645) Anton (or Antonius) Maria Schyrleus (or Schyrle) of Rheita (1597-1660) (in Czech, AntonÃn Maria SÃrek z Reity) was a Czech astronomer and optician. ...
Sir Wilhelm Friedrich Herschel, FRS (Hanover, November 15, 1738 – August 25, 1822 Slough, then in Buckinghamshire now in Berkshire) was a German-born British astronomer and composer who became famous for discovering the planet Uranus, and made many other astronomical discoveries. ...
Adjective Uranian Atmospheric characteristics Atmospheric pressure 120 kPa (at the cloud level) Hydrogen 83% Helium 15% Methane 1. ...
It has been suggested that Kantianism be merged into this article or section. ...
Benjamin Franklin by Jean-Baptiste Greuze 1777 For the former mayor of Nepean, see Ben Franklin (politician) Benjamin Franklin (January 17, 1706–April 17, 1790) was one of the most prominent of Founders and early political figures and statesmen of the United States. ...
The Age of Enlightenment refers to the 18th century in European philosophy, and is often thought of as part of a larger period which includes the Age of Reason. ...
The Sun is the star at the centre of our Solar system. ...
Crust composition Oxygen 43% Silicon 21% Aluminium 10% Calcium 9% Iron 9% Magnesium 5% Titanium 2% Nickel 0. ...
Extraterrestrials and the Modern era This enthusiasm towards 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 highpoint for belief in extraterrestrials in the West: 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 other large moons of our system which have been visited appear similarly lifeless, though interesting geothermic forces observed (Io's volcanism, Europa's ocean, Titan's thick atmosphere) has underscored how broad the range of potentially habitable environments may be. Finally, the failure of NASA's 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 and emboldened critics who view the search for extraterrestrials as unscientific. [3] (19th century - 20th century - 21st century - more centuries) Decades: 1900s 1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s As a means of recording the passage of time, the 20th century was that century which lasted from 1901–2000 in the sense of the Gregorian calendar (1900–1999 in the...
In the history of science, the scientific revolution was the period that roughly began with the discoveries of Kepler, Galileo, and others at the dawn of the 17th century, and ended with the publication of the Philosophiae Naturalis Principia Mathematica in 1687 by Isaac Newton. ...
Adjective Venusian or (rarely) Cytherean (*min temperature refers to cloud tops only) Atmospheric characteristics Atmospheric pressure 9. ...
Amongst the findings from the Opportunity rover is the presence of hematite on Mars in the form of small spheres on the Meridiani Planum. ...
Io or io may stand for: In Greek mythology, Io (IPA or ) was the daughter of Inachus, a river god. ...
It has been suggested that this article or section be merged with Europe (disambiguation). ...
Atmospheric characteristics Pressure 160 kPa Nitrogen 95 percent Methane 5 percent Titan (tye-tun, Greek Τιτάνας) is the largest moon of Saturn and the second largest moon in the solar system, after Jupiters moon Ganymede. ...
NASA Logo Listen to this article · (info) This audio file was created from the revision dated 2005-09-01, and does not reflect subsequent edits to the article. ...
SETI (pronounced , to rhyme with Betty) stands for Search for Extra-Terrestrial Intelligence. ...
Thus, the three decades preceding the turn of the second millenium 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 ("All we know for sure is that the sky is not littered with powerful microwave transmitters" in the words of SETI's Frank Drake). 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. Professor Frank Drake Frank Drake (born May 28, 1930, Chicago, Illinois) is an American astronomer and astrophysicist. ...
Understanding planetary habitability is partly an extrapolation of Earth conditions Planetary habitability is the measure of an astronomical body’s potential for developing and sustaining life. ...
Infrared image of the star GQ Lupi (A) orbited by a planet (b) at a distance of approximately 20 times the distance between Jupiter and our Sun. ...
Amongst the general public belief and interest in extraterrestrials remains high and skepticism towards galaxy-exploring alien civilizations is not shared by many individuals. At present, some enthusiasts in the topic believe that extraterrestrial beings regularly visit or have visited the Earth. Some think that unidentified flying objects observed in the skies are in fact sightings of the spacecraft of intelligent extraterrestrials, and even claim to have met such beings. Crop circle patterns have also been attributed to the actions of extraterrestrials, although many were later found to be hoaxes. While at least one recent scientific paper published in a respected, peer-reviewed journal has urged a re-evaluation of the UFO phenomenon (Deardorff et al., 2005) [4], as of this time mainstream scientific opinion holds that such claims are unsupportable by the evidence currently available and unlikely to be true. UFO redirects here. ...
A crop circle pattern Crop circles are areas of cereal or similar crops that have been systematically flattened to form various geometric patterns. ...
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 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. A mission is also proposed to Europa, one of Jupiter's moons with a liquid water layer under its surface, which might contain life. Presentation of the solar system (not to scale) The solar system is comprised of our Sun and the retinue of celestial objects gravitationally bound to it. ...
Worlds second largest Meteorite in Culiacan, Mexico A meteorite is a relatively small extra-terrestrial body that reaches the Earths surface. ...
Atmospheric characteristics Atmospheric pressure 1 µPa Oxygen 100% Europa (ew-roe-pa, /juro:pa/ listen [â–¶](audio help), Greek ΕυÏώπη) is a moon of the planet Jupiter, smallest of the four Galilean moons. ...
Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ...
There is some limited evidence that microbial life might possibly exist or have existed on Mars. An experiment on the Viking Mars lander reported gas emissions from heated Martian soil that some argue are consistent with the presence of microbes. However, the lack of corroborating evidence from other experiments on the Viking indicates that a non-biological reaction is a more likely hypothesis. Independently in 1996 structures resembling bacteria were reportedly discovered in a meteorite, ALH84001, known to be formed of rock ejected from Mars. Again, this report is vigorously disputed. NASAs Viking program consisted of two unmanned space missions to Mars, Viking 1 and Viking 2. ...
1996 (MCMXCVI) is a leap year starting on Monday of the Gregorian calendar, and was designated the International Year for the Eradication of Poverty. ...
Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ...
meteorite fragment ALH84001 ALH84001 (representing Allen Hills 1984 #001) is a meteorite found in Allen Hills, Antarctica in December 1984 by a team of US meteorite hunters from the ANSMET project, among 7,000 others. ...
In February 2005, NASA scientists reported that they had found strong evidence of present life on Mars (Berger, 2005). 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 officials soon denied the scientists’ claims, and Stoker herself backed off from her initial assertions (spacetoday.net, 2005). However, only a few days after Stoker and Lemke made their claims, scientists from the European Space Agency reported that their own measurements of methane on Mars suggested an organic origin (Michelson, 2005). NASA Logo Listen to this article · (info) This audio file was created from the revision dated 2005-09-01, and does not reflect subsequent edits to the article. ...
Amongst the findings from the Opportunity rover is the presence of hematite on Mars in the form of small spheres on the Meridiani Planum. ...
Aerial View of Moffett Field and NASA Ames Research Center. ...
The European Space Agency (ESA), established in 1975, is an inter-governmental organisation dedicated to exploration of space with currently 17 member states. ...
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 of scientists attending the conference at which the European Space Agency presented its findings, 75 percent of the scientists at the conference reported to believe that life once existed on Mars; 25 percent reported a belief that life currently exists there (Michelson, 2005).
Indirect search It is theorised that any technological society in space will be transmitting information. Projects such as SETI are conducting an astronomical search for radioactivity that would confirm the presence of intelligent life. A related suggestion is that aliens might broadcast pulsed and continuous laser signals in the optical as well as infrared spectrum [5]; laser signals have the advantage of not "smearing" in the interstellar medium and may prove more conducive to communication between the stars. SETI (pronounced , to rhyme with Betty) stands for Search for Extra-Terrestrial Intelligence. ...
The range of sizes in which lasers exist is immense, extending from microscopic diode lasers (top) to football field sized neodymium glass lasers (bottom) used for inertial confinement fusion. ...
Astronomers also search for extrasolar planets that would be conducive to life. 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). The Terrestrial Planet Finder is one NASA programme on the horizon that has generated optimism over the potential discovery of habitable planets. It has been argued that one of the best candidates for the discovery of life-supporting planets may be Alpha Centauri, the closest star system to Earth, given that two of the three stars in the system are broadly sun-like. Infrared Image of a possible extrasolar planet (lower left) in the Constellation Taurus, taken by the Hubble Space Telescope. ...
Atomic absorption spectroscopy in analytical chemistry is a technique for determining the concentration of a particular metal element within a sample. ...
General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ...
The Terrestrial Planet Finder (TPF) is a proposed NASA telescope system capable of detecting extrasolar terrestrial planets. ...
The position of Alpha Centauri Alpha Centauri (α Cen / α Centauri) is the brightest star system (a triple star system) in the southern constellation of Centaurus, and contains the fourth brightest star in the sky, with an apparent visual magnitude of −0. ...
Extraterrestrial life in the Solar System Many bodies in the Solar System have been suggested as being likely to contain life. The most commonly suggested ones are listed below; of these, four of the five are moons thought to have large bodies of underground liquid, and life may have evolved there in a similar fashion to deep sea vents. - Mars - The best known of the other planets and moons in the Solar system. There was liquid water on Mars in the past and there may be liquid water beneath the surface. Recently, methane was found in the atmosphere of Mars.
- Titan - Only known moon with a significant atmosphere. Recently visited by the Huygens probe. Latest discoveries indicate that there is no global or widespread ocean, but small and/or seasonal liquid hydrocarbon lakes are still possible.
- Europa - probably has a salt ocean under a thick ice crust.
- Ganymede - Jupiter's largest moon, and indeed the largest moon in the entire solar system
- Enceladus - May have liquid water beneath its surface. [6]
Numerous other bodies have been suggested as potentially life-bearing. For example, atmospheric life has been hypothesised on Venus and the gas giants. Fred Hoyle also proposed that microbial life might exist on comets. Some Earth microbes also managed to survive on a lunar probe for some years. It is considered highly unlikely that complex multicellular organisms exist in any of these places. Amongst the findings from the Opportunity rover is the presence of hematite on Mars in the form of small spheres on the Meridiani Planum. ...
R-phrases S-phrases , , , Flash point −188 °C Autoignition temperature 537 °C Explosive limits 5–15% Supplementary data page Structure and properties n, εr, etc. ...
Atmospheric characteristics Pressure 160 kPa Nitrogen 95 percent Methane 5 percent Titan (tye-tun, Greek Τιτάνας) is the largest moon of Saturn and the second largest moon in the solar system, after Jupiters moon Ganymede. ...
A scale replica of the probe An artists impression of the Huygens probe as it descends through Titans murky, brownish-orange atmosphere of nitrogen and carbon-based molecules, beaming its findings to the distant Cassini orbiter. ...
Atmospheric characteristics Atmospheric pressure 1 µPa Oxygen 100% Europa (ew-roe-pa, /juro:pa/ listen [â–¶](audio help), Greek ΕυÏώπη) is a moon of the planet Jupiter, smallest of the four Galilean moons. ...
In chemistry, salt is a term used for ionic compounds composed of positively charged cations and negatively charged anions, so that the product is neutral and without a net charge. ...
Atmospheric characteristics Atmospheric pressure trace Oxygen 100% Ganymede (IPA: , gan-i-meed, Greek Γανυμήδης) is Jupiters largest moon, and indeed the largest moon in the entire solar system; it is larger in diameter than Mercury but only about half its mass. ...
Adjective Jovian Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ...
[4]; [5] Atmospheric characteristics Pressure trace, signficant spatial variability [6] Water Vapor 65% [7] Hydrogen 20% [8] Other CO2, CO, N2 [9] Enceladus (en-sel-a-dus, Greek ΕγκÎλαδος) is a moon of Saturn discovered in 1789 by William Herschel. ...
Sir Fred Hoyle Sir Fred Hoyle (June 24, 1915 in Yorkshire – August 20in Bournemouth, England, 2001) was a British astronomer, notable for a number of his theories that run counter to current astronomical opinion, and a writer of science fiction, including a number of books co-authored by his son...
Dealing with extraterrestrial life If intelligent extraterrestrial life is found and it is possible to communicate with it, the people of the world and their governments will need to determine how to manage those interactions. The development of policy guidelines for dealing with extraterrestrial beings and territory has been considered by authors such as Michael Salla and Alfred Webre and termed exopolitics. Alfred Lambremont Webre (born May 24, 1942) is an author, lawyer, environmentalist and a space activist who promotes the ban of space weapons. ...
Exopolitics is the politics related to what should happen if intelligent extraterrestrial life is found and we are able to communicate with it. ...
See also The alien invasion is a common theme in science fiction stories and film, in which a technologically-superior extraterrestrial society invades Earth with the intent to replace human life, or to enslave it under a colonial system. ...
An anomalous phenomenon is an observed phenomenon for which there is no suitable explanation in the context of a specific body of scientific knowledge (e. ...
Seth Shostak and Molly Bentley performing a social experiment for Skeptical Sunday. ...
Astrobiology is an interdisciplinary field, combining aspects of astronomy, biology and geology, which considers the question of whether extraterrestrial life exists and if so, then what are its origin, distribution, and evolution. ...
Astrosociobiology (also referred to as exosociobiology and xenosociology) is the speculative scientific study of extraterrestrial civilizations and their possible social characteristics and developmental tendencies. ...
Back-contamination is the informal but widely-employed name for the introduction of microbial extraterrestrial organisms into Earths biosphere. ...
The Drake equation (also known as the Green Bank equation or the Sagan equation) is a famous result in the speculative fields of xenobiology, astrosociobiology and the search for extraterrestrial intelligence. ...
In popular fiction and conspiracy theories, life forms, especially intelligent life forms, that are of extraterrestrial origin, i. ...
Radio telescope observations play a role in researching the Fermi paradox The Fermi paradox is a paradox proposed by the physicist Enrico Fermi that questions the probability of finding intelligent extraterrestrial life. ...
First contact is a common science-fictional theme about the first meeting between humans and aliens. ...
Professor Frank Drake Frank Drake (born May 28, 1930, Chicago, Illinois) is an American astronomer and astrophysicist. ...
In astronomy a habitable zone (HZ) is a region of space where conditions are favorable for the creation of life. ...
Kardashev scale projections ranging from 1900 to 2100. ...
This is a list of space aliens that have appeared in various works of fiction featuring aliens. ...
Panspermia is the hypothesis that the seeds of life are prevalent throughout the universe, and furthermore that life on Earth began by such seeds landing on Earth and propagating themselves. ...
Understanding planetary habitability is partly an extrapolation of Earth conditions Planetary habitability is the measure of an astronomical body’s potential for developing and sustaining life. ...
The rare Earth hypothesis is a response to the Fermi paradox which explains why we might expect a planet such as Earth to be very rare. ...
Scientific skepticism or rational skepticism (UK spelling, scepticism) sometimes referred to as skeptical inquiry, is a scientific, or practical, epistemological position (or paradigm) in which one questions the veracity of claims unless they can be scientifically verified. ...
Categories: Possible copyright violations ...
Professor Seth Shostak Seth Shostak is an American astronomer. ...
SETI (pronounced , to rhyme with Betty) stands for Search for Extra-Terrestrial Intelligence. ...
The Greys have landed! Alien mannequin at International UFO Museum & Research Center; Roswell, NM, USA Greys (also known as Zetas or Reticulians after the ζ Reticuli star system) are the type of intelligent extraterrestrial life that appears most commonly in modern conspiracy theories, particularly UFO conspiracy theories and other UFO-related...
References - Jack Cohen and Ian Stewart (2002): Evolving the Alien: The Science of Extraterrestrial Life, Ebury Press, ISBN 0-091-87927-2
- J. Deardorff, B. Haisch, B. Maccabee, Harold E. Puthoff (2005). Inflation-Theory Implications for Extraterrestrial Visitation, Journal of the British Interplanetary Society, 58: 43–50. (pdf file)
- Berger, Brian (2005). Exclusive: NASA Researchers Claim Evidence of Present Life on Mars. Posted Feb. 16, 2005.
- spacetoday.net (2005). NASA denies Mars life reports. Posted Feb 19, 2005.
- Michelson, Marcel (2005). European Scientists Believe in Life on Mars. Posted Feb 25, 2005.
- John C. Baird. 1987. The Inner Limits of Outer Space: A Psychologist Critiques Our Efforts to Communicate With Extraterrestrial Beings. Hanover: University Press of New England. ISBN 0-87451-406-1
- Donald Goldsmith. 1997. The Hunt for Life on Mars. New York: A Dutton Book. ISBN 0525943366
- Michael T. Lemnick. 1998. Other Worlds: The Search for Life in the Universe. New York: A Touchstone Book.
- Cliff Pickover. 2003 The Science of Aliens New York: Basic Books. ISBN 0-465-07315-8
See: Jack Cohen, biologist and special effects consultant. ...
There have been several well-known people named Ian Stewart, including: Ian Stewart (athlete) Ian Stewart (mathematician) Ian Stewart (musician) Ian Stewart (racing driver) Ian Stewart (Conservative politician) - formely MP for Hitchin Ian Stewart (Labour politician) - MP for Eccles Ian Stewart (serial killer) - usually known as Ian Brady Ian Stewart...
Evolving the Alien: The Science of Extraterrestrial Life (second edition publised as What Does a Martian Look Like? The Science of Extraterrestrial Life) is a book about xenobiology by biologist Jack Cohen and mathematician Ian Stewart. ...
Harold E. Puthoff, PhD, is an American physicist. ...
The Journal of the British Interplanetary Society (JBIS) is a technical scientific journal, first published in 1934. ...
Clifford A. Pickover is a writer in the fields of science, mathematics, and science fiction. ...
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