साल: रिवीजन सभ के बीचा में अंतर
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लाइन 4:
===एस॰आइ॰ (SI) प्रीफिक्स===
<!-- This section is linked from [[Cretaceous]], from [[Template:Geologic time scale]] and from [[Theropoda]]. -->
* {{Anchor|Megaannus|Megaannum}} ''Ma'' (for megaannus), is a unit of [[time]] equal to one [[million]] (10<sup>6</sup>) years. It is commonly used in scientific disciplines such as geology, paleontology, and [[celestial mechanics]] to signify very long time periods into the past or future. For example, the [[dinosaur]] species ''[[Tyrannosaurus|Tyrannosaurus rex]]'' was abundant approximately ''66 Ma'' (66 million years) ago (''ago'' may not always be mentioned; if the quantity is specified while not explicitly discussing a duration, one can assume that "ago" is implied; the alternative "mya" unit includes "ago" explicitly). In astronomical applications, the year used is the Julian year of precisely 365.25 days. In geology and paleontology, the year is not so precise and varies depending on the author.▼
* {{Anchor|Gigaannus|Gigaannum}} ''Ga'' (for gigaannus), is a unit of time equal to 10<sup>9</sup> years (one [[1000000000 (number)|billion]] on the [[long and short scales|short scale]], one [[milliard]] on the [[long and short scales|long scale]]). It is commonly used in scientific disciplines such as [[physical cosmology|cosmology]] and geology to signify extremely long time periods in the past. For example, the formation of the Earth occurred approximately ''4.57 Ga'' (4.57 billion years) ago.▼
* {{Anchor|Teraannus|Teraannum}} ''Ta'' (for teraannus), is a unit of time equal to 10<sup>12</sup> years (one [[1000000000000 (number)|trillion]] on the short scale, one billion on the long scale). It is an extremely long unit of time, about 70 times as long as the [[age of the universe]]. It is the same order of magnitude as the expected life span of a small [[red dwarf]].▼
* {{Anchor|Petaannus|Petaannum}} ''Pa'' (for petaannus), is a unit of time equal to 10<sup>15</sup> years (one [[10^15|quadrillion]] on the short scale, one [[billiard (number)|billiard]] on the long scale). The half-life of the nuclide [[cadmium]]-113 is about 8 Pa.<ref>{{cite journal| author = P. Belli| display-authors = etal| title = Investigation of β decay of <sup>113</sup>Cd| journal = [[Phys. Rev. C]] |volume = 76|page = 064603|year = 2007 |doi = 10.1103/PhysRevC.76.064603|bibcode = 2007PhRvC..76f4603B| issue = 6 }}</ref> <!--The half-life of the nuclear isomer [[tantalum]]-180m is about 1 Pa.<ref>[http://www.eurekalert.org/features/doe/2005-08/drnl-ttp082205.php Testing the physics of nuclear isomers] ''Eurekalert'' (August 2005)</ref> (error in source -- it in not half-life, it is the lower limit on half-life, that means that the half-life can be, for example, 1e21 yr or 1e29 yr or any other value > 1e15 yr. The decay of Ta-180m had never been observed).--> This symbol coincides with that for the [[pascal (unit)|pascal]] without a multiplier prefix, though both are infrequently used and context will normally be sufficient to distinguish time from pressure values.▼
* {{Anchor|Exaannus|Exaannum}} ''Ea'' (for exaannus), is a unit of time equal to 10<sup>18</sup> years (one [[quintillion]] on the short scale, one trillion on the long scale). The half-life of [[tungsten]]-180 is 1.8 Ea.<ref>{{cite journal| author = F. A. Danevich| display-authors = etal| title = α activity of natural tungsten isotopes| journal = [[Phys. Rev. C]] |volume = 67|page = 014310|year = 2003| arxiv = nucl-ex/0211013|doi = 10.1103/PhysRevC.67.014310|bibcode = 2003PhRvC..67a4310D }}</ref>▼
* {{Anchor|Kiloannus|Kiloannum}} ''ka'' (किलोएनस (kiloannus) खातिर), एक सहस्राब्दि या मिलेनियम के कहल जाला आ ई एक हजार साल के बराबर होला। एकर इस्तेमाल खासतौर पर भूबिज्ञान, पैलियोओंटोलॉजी आ पुरातत्व बिज्ञान में होलोसीन के आ प्लीस्टोसीन काल के घटना खातिर होला।
▲* {{Anchor|Megaannus|Megaannum}} ''Ma'' (
▲* {{Anchor|Gigaannus|Gigaannum}} ''Ga'' (
▲* {{Anchor|Teraannus|Teraannum}} ''Ta'' (
▲* {{Anchor|Petaannus|Petaannum}} ''Pa'' (
▲* {{Anchor|Exaannus|Exaannum}} ''Ea'' (
==संदर्भ==
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