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Detailed Logarithmic Timeline
This timeline shows the whole history of the universe, the Earth, and mankind in one table. Each row is defined in ''years ago'', that is, years before the present date, with the earliest times at the top of the chart. In each table cell on the right, references to events or notable people are given, more or less in chronological order within the cell. Each row corresponds to a change in log (time before present, that is, the logarithm of the time before the present) of about 0.1 (using base 10 logarithm). The dividing points are taken from the R′′20 Renard numbers. Thus each row represent about 21% of the time from its beginning until the present. The table is divided into sections with subtitles. Note that each such section contains about 68% of all the time from the beginning of the section until now. Past 13,800 million years ago to 5500 million years ago 5500 million years ago to 1800 million years ago 1800 million years ago to 550 million years ago 550 millio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
History Of The Universe
History (derived ) is the systematic study and the documentation of the human activity. The time period of event before the invention of writing systems is considered prehistory. "History" is an umbrella term comprising past events as well as the memory, discovery, collection, organization, presentation, and interpretation of these events. Historians seek knowledge of the past using historical sources such as written documents, oral accounts, art and material artifacts, and ecological markers. History is not complete and still has debatable mysteries. History is also an academic discipline which uses narrative to describe, examine, question, and analyze past events, and investigate their patterns of cause and effect. Historians often debate which narrative best explains an event, as well as the significance of different causes and effects. Historians also debate the nature of history as an end in itself, as well as its usefulness to give perspective on the problems of the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atom
Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has no neutrons. Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms. Atoms are extremely small, typically around 100 picometers across. They are so small that accurately predicting their behavior using classical physics, as if they were tennis balls for example, is not possible due to quantum effects. More than 99.94% of an atom's mass is in the nucleus. The protons have a positive electric charge, the electrons have a negative electric charge, and the neutrons have no electric charge. If the number of protons and electrons are equal, then the atom is electrically neutral. If an atom has more or fewer electrons than protons, then it has an overall negative or positive charge, respectively – such atoms are called ions. The electrons of an at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gas Giant
A gas giant is a giant planet composed mainly of hydrogen and helium. Gas giants are also called failed stars because they contain the same basic elements as a star. Jupiter and Saturn are the gas giants of the Solar System. The term "gas giant" was originally synonymous with "giant planet". However, in the 1990s, it became known that Uranus and Neptune are really a distinct class of giant planets, being composed mainly of heavier volatile substances (which are referred to as "ices"). For this reason, Uranus and Neptune are now often classified in the separate category of ice giants. Jupiter and Saturn consist mostly of hydrogen and helium, with heavier elements making up between 3 and 13 percent of their mass.The Interior of Jupiter, Guillot et al., in ''Jupiter: The Planet, Satellites and Magnetosphere'', Bagenal et al., editors, Cambridge University Press, 2004 They are thought to consist of an outer layer of compressed molecular hydrogen surrounding a layer of liquid metalli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PSR B1620-26 B
PSR may refer to: Organizations * Pacific School of Religion, Berkeley, California, US * Palestinian Center for Policy and Survey Research * Physicians for Social Responsibility, US ;Political parties: * Revolutionary Socialist Party (Portugal) (''Partido Socialista Revolucionário'') * Romanian Socialist Party (present-day) Places * Abruzzo Airport (IATA airport code), near Pescara, Italy * Pasir Ris MRT station (MRT station abbreviation), Singapore * Pioneer Scout Reservation, a Boy Scout camp in Ohio, US Science and technology * Pulsar, a kind of star * Primary radar * Perimeter surveillance radar * Posthumous sperm retrieval from dead men Computing * PHP Standard Recommendation * Predictive state representation of a system * Problem Steps Recorder, psr.exe, a Microsoft utility * Panel Self-Refresh in Embedded DisplayPort Law enforcement and military * US Precision Sniper Rifle * PSR-90, a Pakistani Precision Sniper Rifle Other uses * Portuguese Sign Language (ISO ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galaxy Merger
Galaxy mergers can occur when two (or more) galaxies collide. They are the most violent type of galaxy interaction. The gravitational interactions between galaxies and the friction between the gas and dust have major effects on the galaxies involved. The exact effects of such mergers depend on a wide variety of parameters such as collision angles, speeds, and relative size/composition, and are currently an extremely active area of research. Galaxy mergers are important because the merger rate is a fundamental measurement of galaxy evolution. The merger rate also provides astronomers with clues about how galaxies bulked up over time. Description During the merger, stars and dark matter in each galaxy become affected by the approaching galaxy. Toward the late stages of the merger, the gravitational potential (i.e. the shape of the galaxy) begins changing so quickly that star orbits are greatly altered, and lose any trace of their prior orbit. This process is called “viole ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hubble Deep Field
The Hubble Deep Field (HDF) is an image of a small region in the constellation Ursa Major, constructed from a series of observations by the Hubble Space Telescope. It covers an area about 2.6 arcminutes on a side, about one 24-millionth of the whole sky, which is equivalent in angular size to a tennis ball at a distance of 100 metres. The image was assembled from 342 separate exposures taken with the Space Telescope's Wide Field and Planetary Camera 2 over ten consecutive days between December 18 and 28, 1995. The field is so small that only a few foreground stars in the Milky Way lie within it; thus, almost all of the 3,000 objects in the image are galaxies, some of which are among the youngest and most distant known. By revealing such large numbers of very young galaxies, the HDF has become a landmark image in the study of the early universe. Three years after the HDF observations were taken, a region in the south celestial hemisphere was imaged in a similar way and na ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HCM-6A
HCM-6A is an LAE galaxy that was found in 2002 by Esther Hu and Lennox Cowie from the University of Hawaii and Richard McMahon from the University of Cambridge, using the Keck II Telescope in Hawaii. HCM-6A is located behind the Abell 370 galactic cluster, near M77 in the constellation Cetus, which enabled the astronomers to use Abell 370 as a gravitational lens to get a clearer image of the object. National Astronomical Observatory of Japan, September 13, 2006 HCM-6A was the farthest object known at the time of its discovery. It exceeded SSA22−HCM1 (''z'' = 5.74) as the most distant normal galaxy known, and quasar [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The New York Times
''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid digital subscribers. It also is a producer of popular podcasts such as '' The Daily''. Founded in 1851 by Henry Jarvis Raymond and George Jones, it was initially published by Raymond, Jones & Company. The ''Times'' has won 132 Pulitzer Prizes, the most of any newspaper, and has long been regarded as a national "newspaper of record". For print it is ranked 18th in the world by circulation and 3rd in the U.S. The paper is owned by the New York Times Company, which is publicly traded. It has been governed by the Sulzberger family since 1896, through a dual-class share structure after its shares became publicly traded. A. G. Sulzberger, the paper's publisher and the company's chairman, is the fifth generation of the family to head the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Journal Of Astrobiology
The ''International Journal of Astrobiology'' (IJA) is a peer-reviewed scientific journal established in 2002 and published by Cambridge University Press that covers research on the prebiotic chemistry, origin, evolution, distribution, and future of life on Earth and beyond, SETI ( Search for extraterrestrial intelligence), societal and educational aspects of astrobiology. It also contains papers in astronomy, space science, planetary science, and biology that have a strong connection to astrobiology. Occasional issues are dedicated to research papers from international astrobiology meetings. The editor-in-chief is Rocco Mancinelli (NASA). According to the ''Journal Citation Reports'', the journal has a 2019 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a scientometric index calculated by Clarivate that reflects the yearly mean number of citations of articles published in the last two years in a given journal, as ... of 2.026. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quasar
A quasar is an extremely luminous active galactic nucleus (AGN). It is pronounced , and sometimes known as a quasi-stellar object, abbreviated QSO. This emission from a galaxy nucleus is powered by a supermassive black hole with a mass ranging from millions to tens of billions of solar masses, surrounded by a gaseous accretion disc. Gas in the disc falling towards the black hole heats up because of friction and releases energy in the form of electromagnetic radiation. The radiant energy of quasars is enormous; the most powerful quasars have luminosities thousands of times greater than that of a galaxy such as the Milky Way. Usually, quasars are categorized as a subclass of the more general category of AGN. The redshifts of quasars are of cosmological origin. The term originated as a contraction of "quasi-stellar '' tar-like' radio source"—because quasars were first identified during the 1950s as sources of radio-wave emission of unknown physical origin—and when ident ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 140283
HD 140283 (also known as the Methuselah star) is a metal-poor subgiant star about 190 light years away from the Earth in the constellation Libra, near the boundary with Ophiuchus in the Milky Way Galaxy. Its apparent magnitude is 7.205. It is one of the oldest stars known. The star's light is somewhat blueshifted as it is moving toward rather than away from the Earth and it has been known to astronomers for over a century as a high-velocity star based on its other vectors (proper motion). An early spectroscopic analysis by Joseph W. Chamberlain and Lawrence Aller revealed it to have a substantially lower metal content than the Sun. Modern spectroscopic analyses find an iron content about a factor of 250 lower than that of the Sun. It is one of the closest metal-poor ( Population II) stars to Earth. The star was already known by 1912 when W. S. Adams measured its astrometry using a spectrograph in the Mount Wilson Observatory. Age and significa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galaxy Formation And Evolution
The study of galaxy formation and evolution is concerned with the processes that formed a heterogeneous universe from a homogeneous beginning, the formation of the first galaxies, the way galaxies change over time, and the processes that have generated the variety of structures observed in nearby galaxies. Galaxy formation is hypothesized to occur from structure formation theories, as a result of tiny quantum fluctuations in the aftermath of the Big Bang. The simplest model in general agreement with observed phenomena is the Lambda-CDM model—that is, that clustering and merging allows galaxies to accumulate mass, determining both their shape and structure. Commonly observed properties of galaxies Because of the inability to conduct experiments in outer space, the only way to “test” theories and models of galaxy evolution is to compare them with observations. Explanations for how galaxies formed and evolved must be able to predict the observed properties and types of galax ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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