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Earth Analogue
An Earth analog, also called an Earth twin or second Earth, is a planet or moon with environmental conditions similar to those found on Earth. The term Earth-like planet is also used, but this term may refer to any terrestrial planet. The possibility is of particular interest to astrobiologists and astronomers under reasoning that the more similar a planet is to Earth, the more likely it is to be capable of sustaining complex extraterrestrial life. As such, it has long been speculated and the subject expressed in science, philosophy, science fiction and popular culture. Advocates of space colonization and space and survival have long sought an Earth analog for settlement. In the far future, humans might artificially produce an Earth analog by terraforming. Before the scientific search for and study of extrasolar planets, the possibility was argued through philosophy and science fiction. Philosophers have suggested that the size of the universe is such that a near-identical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Eleven or 11 may refer to: *11 (number) * One of the years 11 BC, AD 11, 1911, 2011 Literature *Eleven (novel), ''Eleven'' (novel), a 2006 novel by British author David Llewellyn *''Eleven'', a 1970 collection of short stories by Patricia Highsmith *''Eleven'', a 2004 children's novel in The Winnie Years by Lauren Myracle *''Eleven'', a 2008 children's novel by Patricia Reilly Giff *''Eleven'', a short story by Sandra Cisneros Music *Eleven (band), an American rock band *Eleven: A Music Company, an Australian record label *Up to eleven, an idiom from popular culture, coined in the movie ''This Is Spinal Tap'' Albums *11 (The Smithereens album), ''11'' (The Smithereens album), 1989 *11 (Ua album), ''11'' (Ua album), 1996 *11 (Bryan Adams album), ''11'' (Bryan Adams album), 2008 *11 (Sault album), ''11'' (Sault album), 2022 *Eleven (Harry Connick, Jr. album), ''Eleven'' (Harry Connick, Jr. album), 1992 *Eleven (22-Pistepirkko album), ''Eleven'' (22-Pistepirkko album), 1998 *Eleven ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Universe
The universe is all of space and time and their contents. It comprises all of existence, any fundamental interaction, physical process and physical constant, and therefore all forms of matter and energy, and the structures they form, from sub-atomic particles to entire Galaxy filament, galactic filaments. Since the early 20th century, the field of cosmology establishes that space and time emerged together at the Big Bang ago and that the Expansion of the universe, universe has been expanding since then. The observable universe, portion of the universe that can be seen by humans is approximately 93 billion light-years in diameter at present, but the total size of the universe is not known. Some of the earliest Timeline of cosmological theories, cosmological models of the universe were developed by ancient Greek philosophy, ancient Greek and Indian philosophy, Indian philosophers and were geocentric model, geocentric, placing Earth at the center. Over the centuries, more prec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astrobiology (journal)
''Astrobiology'' is a peer review, peer-reviewed scientific journal covering research on the abiogenesis, origin, evolution, distribution and future of life across the universe. The journal's scope includes astrobiology, astrophysics, astropaleontology, bioastronomy, cosmochemistry, ecogenomics, exobiology, extremophiles, geomicrobiology, gravitational biology, life detection technology, meteoritics, origins of life, planetary geoscience, planetary protection, prebiotic chemistry, space exploration technology and terraforming. Abstracting and indexing This journal is indexed by the following services: According to the ''Journal Citation Reports'', the journal has a 2019 impact factor of 4.091. References External links * Astrobiology journals Mary Ann Liebert academic journals Academic journals established in 2001 Bimonthly journals English-language journals {{astrobiology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earliest Known Life Forms
The earliest known life forms on Earth may be as old as 4.1 billion years (or Year#SI prefix multipliers, Ga) according to biologically fractionated graphite inside a single zircon grain in the Jack Hills range of Australia. The earliest evidence of life found in a Stratigraphic unit, stratigraphic unit, not just a single mineral grain, is the 3.7 Ga Metasedimentary rock, metasedimentary rocks containing graphite from the Isua Greenstone Belt, Isua Supracrustal Belt in Greenland. The earliest direct known life on Earth are stromatolite fossils which have been found in 3.480-billion-year-old geyserite uncovered in the Dresser Formation, Dresser Formation of the Pilbara craton, Pilbara Craton of Western Australia. Various Micropaleontology#Microfossils, microfossils of Microorganism, microorganisms have been found in 3.4 Ga rocks, including 3.465-billion-year-old Pilbara craton, Apex chert rocks from the same Australian craton region, and in 3.42 Ga hydrothermal vent precipitates fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Life
Life, also known as biota, refers to matter that has biological processes, such as Cell signaling, signaling and self-sustaining processes. It is defined descriptively by the capacity for homeostasis, Structure#Biological, organisation, metabolism, Cell growth, growth, adaptation, response to stimulus (physiology), stimuli, and reproduction. All life over time eventually reaches a state of death, and none is Immortality, immortal. Many philosophical definitions of living systems have been proposed, such as self-organizing systems. Viruses in particular make definition difficult as they replicate only in Host (biology), host cells. Life exists all over the Earth in air, water, and soil, with many ecosystems forming the biosphere. Some of these are harsh environments occupied only by extremophiles. Life has been studied since ancient times, with theories such as Empedocles's materialism asserting that it was composed of Classical element, four eternal elements, and Aristotle's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astrophysics
Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline, James Keeler, said, astrophysics "seeks to ascertain the nature of the heavenly bodies, rather than their positions or motions in space—''what'' they are, rather than ''where'' they are", which is studied in celestial mechanics. Among the subjects studied are the Sun ( solar physics), other stars, galaxies, extrasolar planets, the interstellar medium, and the cosmic microwave background. Emissions from these objects are examined across all parts of the electromagnetic spectrum, and the properties examined include luminosity, density, temperature, and chemical composition. Because astrophysics is a very broad subject, ''astrophysicists'' apply concepts and methods from many disciplines of physics, including classical mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superhabitable Planet
A superhabitable world is a hypothetical type of planet or moon that is better suited than Earth for the emergence and evolution of life. The concept was introduced in a 2014 paper by René Heller and John Armstrong, in which they criticized the language used in the search for habitable exoplanets and proposed clarifications. The authors argued that knowing whether a world is located within the star's habitable zone is insufficient to determine its habitability, and that the prevailing model of characterization was geocentric or anthropocentric in nature. Instead, they proposed a biocentric model that prioritized characteristics affecting the abundance of life and biodiversity on a world's surface. If a world possesses more diverse flora and fauna than there are on Earth, then it would empirically show that its natural environment is more hospitable to life. To identify such a world, one should consider its geological processes, formation age, atmospheric composition, ocean cov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The New York Times
''The New York Times'' (''NYT'') is an American daily newspaper based in New York City. ''The New York Times'' covers domestic, national, and international news, and publishes opinion pieces, investigative reports, and reviews. As one of the longest-running newspapers in the United States, the ''Times'' serves as one of the country's Newspaper of record, newspapers of record. , ''The New York Times'' had 9.13 million total and 8.83 million online subscribers, both by significant margins the List of newspapers in the United States, highest numbers for any newspaper in the United States; the total also included 296,330 print subscribers, making the ''Times'' the second-largest newspaper by print circulation in the United States, following ''The Wall Street Journal'', also based in New York City. ''The New York Times'' is published by the New York Times Company; since 1896, the company has been chaired by the Ochs-Sulzberger family, whose current chairman and the paper's publ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Milky Way
The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the #Appearance, galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galaxy, which are so far away that they cannot be individually distinguished by the naked eye. The Milky Way is a barred spiral galaxy with a Galaxy#Isophotal diameter, D25 isophotal diameter estimated at , but only about 1,000 light-years thick at the spiral arms (more at the bulge). Recent simulations suggest that a dark matter area, also containing some visible stars, may extend up to a diameter of almost 2 million light-years (613 kpc). The Milky Way has several List of Milky Way's satellite galaxies, satellite galaxies and is part of the Local Group of galaxies, forming part of the Virgo Supercluster which is itself a component of the Laniakea Supercluster. It is estimated to contain 100–400 billion stars and at least that number of pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Dwarf
A red dwarf is the smallest kind of star on the main sequence. Red dwarfs are by far the most common type of fusing star in the Milky Way, at least in the neighborhood of the Sun. However, due to their low luminosity, individual red dwarfs are not easily observed. Not one star that fits the stricter definitions of a red dwarf is visible to the naked eye. Proxima Centauri, the star nearest to the Sun, is a red dwarf, as are fifty of the sixty nearest stars. According to some estimates, red dwarfs make up three-quarters of the fusing stars in the Milky Way. The coolest red dwarfs near the Sun have a surface temperature of about and the smallest have radii about 9% that of the Sun, with masses about 7.5% that of the Sun. These red dwarfs have spectral types of L0 to L2. There is some overlap with the properties of brown dwarfs, since the most massive brown dwarfs at lower metallicity can be as hot as and have late M spectral types. Definitions and usage of the term "red d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Analog
Solar-type stars, solar analogs (also analogues), and solar twins are stars that are particularly similar to the Sun. The stellar classification is a hierarchy with solar twin being most like the Sun followed by solar analog and then solar-type. Observations of these stars are important for understanding better the properties of the Sun in relation to other stars and the habitability of planets. By similarity to the Sun Defining the three categories by their similarity to the Sun reflects the evolution of astronomical observational techniques. Originally, solar-type was the closest that similarity to the Sun could be defined. Later, more precise measurement techniques and improved observatories allowed for greater precision of key details like temperature, enabling the creation of a solar analog category for stars that were particularly similar to the Sun. Later still, continued improvements in precision allowed for the creation of a solar-twin category for near-perfect matches ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circumstellar Habitable Zone
In astronomy and astrobiology, the habitable zone (HZ), or more precisely the circumstellar habitable zone (CHZ), is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure.J. F. Kasting, D. P. Whitmire, R. T. Reynolds, Icarus 101, 108 (1993). The bounds of the HZ are based on Earth's position in the Solar System and the amount of radiant energy it receives from the Sun. Due to the importance of liquid water to Earth's biosphere, the nature of the HZ and the objects within it may be instrumental in determining the scope and distribution of planets capable of supporting Earth-like extraterrestrial life and intelligence. As such, it is considered by many to be a major factor of planetary habitability, and the most likely place to find extraterrestrial liquid water and biosignatures elsewhere in the universe. The habitable zone is also called the Goldilocks zone, a metaphor, allusion and antonomasia of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
