query: what is believed to be the composition of earth 's core

pos: Inner core Based on the relative prevalence of various chemical elements in the Solar System, the theory of planetary formation, and constraints imposed or implied by the chemistry of the rest of the Earth's volume, the inner core is believed to consist primarily of a nickel-iron alloy. Pure iron was found to be denser than the core by approximately 3%, implying the presence of light elements in the core (e.g. silicon, oxygen, sulfur) in addition to the probable presence of nickel. Further, if the primordial and mostly "fluid" (still forming) earth contained any significant mass(es) of elements denser than iron and nickel,

pos: Structure of the Earth to sink toward the center in a process called planetary differentiation (see also the iron catastrophe), while less-dense materials would have migrated to the crust. The core is thus believed to largely be composed of iron (80%), along with nickel and one or more light elements, whereas other dense elements, such as lead and uranium, either are too rare to be significant or tend to bind to lighter elements and thus remain in the crust (see felsic materials). Some have argued that the inner core may be in the form of a single iron crystal. Under laboratory conditions a sample

neg: Geology of Venus structures of ilmenite and perovskite, and gradually becomes more like perovskite until the core boundary is reached. Venus is similar to Earth in size and density, and so probably also in bulk composition, but it does not have a significant magnetic field. Earth's magnetic field is produced by what is known as the core dynamo, consisting of an electrically conducting liquid, the nickel-iron outer core that rotates and is convecting. Venus is expected to have an electrically conductive core of similar composition, and although its rotation period is very long (243.7 Earth days), simulations show that this is adequate to

neg: Super-Earth the relevant planet what the structural composition is. For Gliese 876 d, calculations range from 9,200 km (1.4 Earth radii) for a rocky planet and very large iron core to 12,500 km (2.0 Earth radii) for a watery and icy planet. Within this range of radii the super-Earth Gliese 876 d would have a surface gravity between 1.9g and 3.3g (19 and 32 m/s). However, this planet is not known to transit its host star. The limit between rocky planets and planets with a thick gaseous envelope is calculated with theoretical models. Calculating the effect of the active XUV saturation

neg: Moon was thought to come from Theia and it was announced in 2007 that there was less than a 1% chance that Theia and Earth had identical isotopic signatures. Other Apollo lunar samples had in 2012 the same titanium isotopes composition as Earth, which conflicts with what is expected if the Moon formed far from Earth or is derived from Theia. These discrepancies may be explained by variations of the giant impact hypothesis. The Moon is a differentiated body: it has a geochemically distinct crust, mantle, and core. The Moon has a solid iron-rich inner core with a radius possibly as

neg: Icons of Evolution first seven "icons", they are not used as the "best evidence" of evolution in any of the textbooks. The Miller–Urey experiment was an experiment that simulated what were believed to be the conditions on the early Earth and tested the Oparin–Haldane model for chemical evolution. In "Icons of Evolution" Wells argued that since the atmospheric composition used in the experiment is now known to be incorrect, it should not be used in textbooks. Wells said that current ideas about the atmospheric composition of the early Earth makes this type of chemical synthesis impossible due to the presence of "significant" amounts

neg: Io (moon) it is composed almost entirely of iron, or between for a core consisting of a mix of iron and sulfur. "Galileo"<nowiki>'</nowiki>s magnetometer failed to detect an internal, intrinsic magnetic field at Io, suggesting that the core is not convecting. Modeling of Io's interior composition suggests that the mantle is composed of at least 75% of the magnesium-rich mineral forsterite, and has a bulk composition similar to that of L-chondrite and LL-chondrite meteorites, with higher iron content (compared to silicon) than the Moon or Earth, but lower than Mars. To support the heat flow observed on Io, 10–20% of Io's mantle

neg: Super-Earth phase of G-type stars over the loss of the primitive nebula-captured hydrogen envelopes in extrasolar planets, it's obtained that planets with a core mass of more than 1.5 Earth-mass (1.15 Earth-radius max.), most likely cannot get rid of their nebula captured hydrogen envelopes during their whole lifetime. Other calculations point out that the limit between envelope-free rocky super-Earths and sub-Neptunes is around 1.75 Earth-radii, as 2 Earth-radii would be the upper limit to be rocky (a planet with 2 Earth-radii and 5 Earth-masses with a mean Earth-like core composition would imply that 1/200 of its mass would be in a

neg: Outer core measured to be 2.5 millitesla, 50 times stronger than the magnetic field at the surface. The outer core is not under enough pressure to be solid, so it is liquid even though it has a composition similar to the inner core. Sulfur and oxygen could be present in the outer core. As heat is transferred outward toward the mantle, the net trend is for the inner boundary of the liquid region to freeze, causing the solid inner core to grow. This growth rate is estimated to be 1 mm per year. Outer core The outer core of the Earth is

neg: K2-229 iron-rich composition. It is about 17% larger than Earth by radius, but is almost 2.6 times more massive. Its high density indicates it has a core-mass fraction of about 68%, nearly identical to that of Mercury. It is believed that like Mercury, the huge core of K2-229 is the result of a giant impact event. However, unlike Mercury, it orbits extremely close to its host star, with one orbit taking a little over 14 hours to complete. K2-229b has a temperature of over 1,960 K to 2,330 K, hot enough to melt iron and likely giving it an atmosphere of

neg: Composition of Mars Composition of Mars The composition of Mars covers the branch of the geology of Mars that describes the make-up of the planet Mars. Also like Earth, Mars is a differentiated planet, meaning that it has a central core made up of metallic iron and nickel surrounded by a less dense, silicate mantle and crust. The planet's distinctive red color is due to the oxidation of iron on its surface. Much of what we know about the elemental composition of Mars comes from orbiting spacecraft and landers. (See Exploration of Mars for list.) Most of these spacecraft carry spectrometers and other

neg: Composition of Mars detected in powder drilled from one of the rocks, named "Cumberland", analyzed by the Curiosity rover. Composition of Mars The composition of Mars covers the branch of the geology of Mars that describes the make-up of the planet Mars. Also like Earth, Mars is a differentiated planet, meaning that it has a central core made up of metallic iron and nickel surrounded by a less dense, silicate mantle and crust. The planet's distinctive red color is due to the oxidation of iron on its surface. Much of what we know about the elemental composition of Mars comes from orbiting spacecraft

neg: Astronomy by mutual gravitational attraction. As the Earth is located within the dusty outer arms, there are large portions of the Milky Way that are obscured from view. In the center of the Milky Way is the core, a bar-shaped bulge with what is believed to be a supermassive black hole at its center. This is surrounded by four primary arms that spiral from the core. This is a region of active star formation that contains many younger, population I stars. The disk is surrounded by a spheroid halo of older, population II stars, as well as relatively dense concentrations of

neg: LHS 1140 b over twice the density of Earth. This gives it a surface gravity of 3.25 times that of Earth, even higher than that of Jupiter. To escape the gravity of LHS 1140 b, a craft would have to move at 24 km/s, or nearly 54,000 mph. LHS 1140 b's incredibly high density suggests an iron-rich composition, with an iron-nickle core taking up to 75% of the planet's total mass. For comparison, Earth's core comprises about 17% of its mass, over four times less than LHS 1140 b. The orbit of LHS 1140 b takes 24.737 days to complete, much quicker than

neg: Planetary core larger than the Earth's nevertheless; Jupiter has one 10–30 times heavier than Earth, and exoplanet HD149026 b has a core 67 times the mass of the Earth. In 1798, Henry Cavendish calculated the average density of the earth to be 5.48 times the density of water (later refined to 5.53), this led to the accepted belief that the Earth was much denser in its interior. Following the discovery of iron meteorites, Wiechert in 1898 postulated that the Earth had a similar bulk composition to iron meteorites, but the iron had settled to the interior of the Earth, and later represented

neg: Inner core appears to be improbable, any buoyant convection motions will have to be driven by variations in composition or abundance of liquid in its interior. S. Yoshida and colleagues proposed a novel mechanism whereby deformation of the inner core can be caused by a higher rate of freezing at the equator than at polar latitudes, and S. Karato proposed that changes in the magnetic field might also deform the inner core slowly over time. There is an East–West asymmetry in the inner core seismological data. There is a model which explains this by differences at the surface of the inner core

neg: 6Q0B44E 3 times the distance of the Moon's orbit, over a period of 80 days. Its density has been estimated as around 15 kg/m, too low for natural rock and comparable to that expected for an empty fuel tank. 6Q0B44E was spotted at what is believed to be the brightest part of its orbit, at 19th magnitude. As the object moves away from Earth, its brightness falls on a six-month cycle down to 28th magnitude, severely limiting study of its composition. Ephemerides calculated from the observations suggest that 6Q0B44E probably entered the Earth–Moon system between 2001 and 2003, although it may

neg: NEAR Shoemaker raised over succeeding months to a 200 × 200 km orbit and then slowly decreased and altered to a 35 × 35 km retrograde orbit on December 13, 2000. The mission ended with a touchdown in the "saddle" region of Eros on February 12, 2001. Some scientists claim that the ultimate goal of the mission was to link Eros, an asteroidal body, to meteorites recovered on Earth. With sufficient data on chemical composition, a causal link could be established between Eros and other S-type asteroids, and those meteorites believed to be pieces of S-type asteroids (perhaps Eros itself). Once this

neg: Super-Earth the empirical data points out that Gas Dwarves would be the most usual composition: there is a trend where planets with radii up to 1.5 Earth-radii increase in density with increasing radius, but above 1.5 radii the average planet density rapidly decreases with increasing radius, indicating that these planets have a large fraction of volatiles by volume overlying a rocky core. Similar results are confirmed by other studies. Another discovery about exoplanets' composition is that about the gap or rarity observed for planets between 1.5–2.0 Earth-radii, which is explained by a bimodal formation of planets (rocky Super-Earths below 1.75 and

neg: Mega-Earth orbits a subgiant star. Its composition appears to be mainly rock with a small iron core and a relatively thin steam atmosphere. Mega-Earth A mega-Earth is a massive terrestrial exoplanet that is at least ten times the mass of Earth. Mega-Earths are substantially more massive than super-Earths (terrestrial and ocean planets with masses around 5–10 Earths). The term "mega-Earth" was coined in 2014, when Kepler-10c was revealed to be a Neptune-mass planet with a density considerably greater than that of Earth. However, it has since been determined to be a typical volatile-rich planet. Kepler-10c was the first exoplanet to be

neg: Super-Earth an extended gaseous envelope (gas dwarf or sub-Neptune). A super-Earth of high density is believed to be rocky and/or metallic, like Earth and the other terrestrial planets of the Solar System. A super-Earth's interior could be undifferentiated, partially differentiated, or completely differentiated into layers of different composition. Researchers at Harvard Astronomy Department have developed user-friendly online tools to characterize the bulk composition of the super-Earths. A study on Gliese 876 d by a team around Diana Valencia revealed that it would be possible to infer from a radius measured by the transit method of detecting planets and the mass of

neg: Goldschmidt classification even compared to their crustal abundances, which are typically several orders of magnitude below their solar abundances. However, because they are concentrated in the mantle and core, siderophile elements are believed to be present in the Earth as a whole (including the core) in something approaching their solar abundances. The chalcophile elements include: Ag, As, Bi, Cd, Cu, Ga, Ge, Hg, In, Pb, S, Sb, Se, Sn, Te, Tl and Zn. Chalcophile elements are those that remain on or close to the surface because they combine readily with sulfur and/or some other chalcogen other than oxygen, forming compounds which do

neg: Climate change core, tidal energy from the Moon and heat from the decay of radioactive compounds. Both long- and short-term variations in solar intensity are known to affect global climate. Three to four billion years ago, the Sun emitted only 75% as much power as it does today. If the atmospheric composition had been the same as today, liquid water should not have existed on Earth. However, there is evidence for the presence of water on the early Earth, in the Hadean and Archean eons, leading to what is known as the faint young Sun paradox. Hypothesized solutions to this paradox include

neg: Planetary core has an observed magnetic field, which is believed to be generated within its metallic core. Mercury's core occupies 85% of the planet's radius, making it the largest core relative to the size of the planet in the Solar System; this indicates that much of Mercury's surface may have been lost early in the Solar System's history. Mercury has a solid silicate crust and mantle overlying a solid iron sulfide outer core layer, followed by a deeper liquid core layer, and then a possible solid inner core making a third layer. The composition of Venus' core varies significantly depending on the

neg: Planetary core 10–30 times the mass of the Earth, and this core is likely soluble in the gas envelope above, and so primordial in composition. Since the core still exists, the outer envelope must have originally accreted onto a previously existing planetary core. Thermal contraction/evolution models support the presence of metallic hydrogen within the core in large abundances (greater than Saturn). Saturn has an observed magnetic field generated within its metallic core. Metallic hydrogen is present within the core (in lower abundances than Jupiter). Saturn has a rock and or ice core 10–30 times the mass of the Earth, and this core

neg: Geodynamics of terrestrial exoplanets orbit), there is little concrete knowledge of their composition and geodynamic regime. Therefore, the majority of information and conjectures made about them come from alternative sources. All the rocky planets in the solar system except Earth are generally believed to be in the stagnant lid geodynamic regime. Mars and particularly Venus have evidence of prior resurfacing events, but appear to be tectonically quiescent today. Geodynamic inferences about solar system planets have been extrapolated to exoplanets in order to constrain what kind of geodynamic regimes can be expected given a set of physical criterion such as planetary radius, presence of surface

neg: Planetary core Planetary core The planetary core consists of the innermost layer(s) of a planet; which may be composed of solid and liquid layers. Cores of specific planets may be entirely solid or entirely liquid. In the Solar System, core size can range from about 20% (Moon) to 85% of a planet's radius (Mercury). Gas giants also have cores, though the composition of these are still a matter of debate and range in possible composition from traditional stony/iron, to ice or to fluid metallic hydrogen. Gas giant cores are proportionally much smaller than those of terrestrial planets, though theirs can be considerably

neg: HD 102365 of the abundance of elements other than hydrogen and helium; what astronomers term the metallicity of a star. This star system has a relatively large proper motion. The HR 4523 system is presently located within the Epsilon Indi Moving Group, although it gives itself away as an interloper, since the star is older and has a different composition than the group members. It has space velocity components = . The primary star is believed to be orbited by a Neptune-like planet with a mass 16 times that of the Earth. The orbital period of this planet is 122.1 days. No

neg: Structure of the Earth of the modern value. Seismic measurements show that the core is divided into two parts, a "solid" inner core with a radius of ≈1,220 km and a liquid outer core extending beyond it to a radius of ≈3,400 km. The densities are between 9,900 and 12,200 kg/m in the outer core and 12,600–13,000 kg/m in the inner core. The inner core was discovered in 1936 by Inge Lehmann and is generally believed to be composed primarily of iron and some nickel. Since this layer is able to transmit shear waves (transverse seismic waves), it must be solid. Experimental evidence has

neg: Inge Lehmann Inge Lehmann Inge Lehmann (13 May 1888 – 21 February 1993) was a Danish seismologist and geophysicist. In 1936, she discovered that the Earth has a solid inner core inside a molten outer core. Before that, seismologists believed Earth's core to be a single molten sphere, being unable, however, to explain careful measurements of seismic waves from earthquakes, which were inconsistent with this idea. Lehmann analysed the seismic wave measurements and concluded that Earth must have a solid inner core and a molten outer core to produce seismic waves that matched the measurements. Other seismologists tested and then accepted Lehmann's

neg: Lead–lead dating as 4.55 Byr. Patterson also analyzed terrestrial sediment collected from the ocean floor, which was believed to be representative of the Bulk Earth composition. Because the isotope composition of this sample plotted on the meteorite isochron, it suggested that earth had the same age and origin as meteorites, therefore solving the age of the Earth and giving rise to the name 'geochron'. Lead isotope isochron diagram used by C. C. Patterson to determine the age of the Earth in 1956. Animation shows progressive growth over 4550 million years (Myr) of the lead isotope ratios for two stony meteorites (Nuevo Laredo

neg: Core–shell semiconductor nanocrystal diminish this effect. The use of other substances in the core, such as rare-earth elements and Si, are being explored to reduce toxicity. Other disadvantages include limited commercial availability, variability in surface chemistry, nonspecific binding, and instrument limitation. The size, shape, and composition of the core–shell structure are related to the bandgap, which in turn is related to its optical properties. Thus, by modulating the size, shape, and material of the core, the optics can be tuned and optimized for use in optical devices and applications such as LEDs, detectors, lasers, phosphors, and photovoltaics. Currently, CSSNC LED efficiency is less

neg: Saturn mass is not in the gas phase, because hydrogen becomes a non-ideal liquid when the density is above , which is reached at a radius containing 99.9% of Saturn's mass. The temperature, pressure, and density inside Saturn all rise steadily toward the core, which causes hydrogen to be a metal in the deeper layers. Standard planetary models suggest that the interior of Saturn is similar to that of Jupiter, having a small rocky core surrounded by hydrogen and helium with trace amounts of various volatiles. This core is similar in composition to Earth, but more dense. Examination of Saturn's gravitational

neg: Kepler-10c mass of 15–19 Earth masses. With a radius only 2.35 (2.31 to 2.44) times that of Earth (and so a volume 12–15 times that of Earth), it was believed to be unlikely to contain significant amounts of hydrogen or helium gas, since an outgassed or accreted hydrogen-rich atmosphere would have been lost over the 10.6-billion-year lifetime of the Kepler-10 system. Instead, the composition was believed to be mainly rocky, with a water fraction of 5–20% by mass. The bulk of this water was thought to be likely in the form of high-pressure "hot-ice" phases. However, in July 2017, more careful

neg: Planetary core controversy revolving largely around the pressure and oxidation state of Earth's core during its formation. No geochemical evidence exists to include any radioactive elements in Earth's core. Despite this, experimental evidence has found potassium to be strongly siderophilic at the temperatures associated with core formation, thus there is potential for potassium in planetary cores of planets, and therefore potassium-40 as well. Hafnium/tungsten (Hf/W) isotopic ratios, when compared with a chondritic reference frame, show a marked enrichment in the silicate earth indicating depletion in Earth's core. Iron meteorites, believed to be resultant from very early core fractionation processes, are also depleted.

neg: Geomagnetic jerk at Chambon la Forêt (Europe, long. 2.27°). Moreover, the global jerks seem to occur at slightly different times in different regions; often earlier in the Northern hemisphere than in the Southern hemisphere. These events are believed to be caused by changes in the flow patterns of the liquid outer core of the Earth. Another theory is that they are due to torsional oscillations in the solid inner core of the Earth. There have been claims that they are connected to strong earthquakes. Geomagnetic jerk In geophysics, a geomagnetic jerk or secular geomagnetic variation impulse is a relatively sudden change in

neg: K2-229b massive, implying a composition dominated by a huge iron core, very similar to Mercury. It has been referred to as a large Mercury analogue. K2-229b is a relatively Earth-sized planet, first identified using the transit method, where a planet passes in front of its host star and blocks a tiny fraction of its light. When the planet was first discovered, only its radius was known. It was determined to be 1.165 , or about 16.5% larger than Earth. A planet of this size is most likely rocky with a solid surface, like Earth itself. However, radial velocity measurements using the

neg: Planetary core cores). Using the chondritic reference model and combining known compositions of the crust and mantle, the unknown component, the composition of the inner and outer core, can be determined; 85% Fe, 5% Ni, 0.9% Cr, 0.25% Co, and all other refractory metals at very low concentration. This leaves Earth's core with a 5–10% weight deficit for the outer core, and a 4–5% weight deficit for the inner core; which is attributed to lighter elements that should be cosmically abundant and are iron-soluble; H, O, C, S, P, and Si. Earth's core contains half the Earth's vanadium and chromium, and may

neg: The End League alien power core, releasing a wave of radiation and knocking the Earth off its axis. The resulting radiation kills three billion people, with one in ten thousand of the survivors later developing superhuman abilities. Astonishman's responsibility for the Green Event is a fact of which only he and Dead Lexington are aware. The Norse god Thor is the sole remaining classical god on Earth. Believed to be the only being whose power equaled Astonishman's, Thor goes missing on the day of the Green Event and is believed dead. In reality, he is slain by Divinity using her father's sword (Zeus)

neg: TRAPPIST-1f on the TRAPPIST-1 exoplanets. TRAPPIST-1f has a radius about the same as Earth, at around 1.045 , but only about two thirds of Earth's mass, at around 0.68 . So, it is considered somewhat unlikely to be a fully rocky planet, and extremely unlikely to be an Earth-like one, that is rocky with a large iron core but without a thick hydrogen-helium atmosphere enveloping the planet. Simulations strongly suggest the planet is approximately 20% water by composition. With such a massive water envelope, the pressure and temperature will be high enough to keep the water in a gaseous state and

neg: Sun the core and gradually an inner core of helium has begun to form that cannot be fused because presently the Sun's core is not hot or dense enough to fuse helium. In the current photosphere the helium fraction is reduced, and the metallicity is only 84% of what it was in the protostellar phase (before nuclear fusion in the core started). In the future, helium will continue to accumulate in the core, and in about 5 billion years this gradual build-up will eventually cause the Sun to exit the main sequence and become a red giant. The chemical composition of

neg: Epistle to the Galatians careful research relating to paper construction, handwriting development, and the established principles of textual criticism, scholars can be rather certain about where these errors and changes appeared and what the original text probably said." A majority of scholars agree that Galatians was written between the late 40s and early 50s. although some date the original composition to c. 50–60 AD.. Biblical scholars agree that Galatians is a true example of Paul's writing. The main arguments in favor of the authenticity of Galatians include its style and themes, which are common to the core letters of the Pauline corpus. George S.

neg: Thermal history of the Earth Earth's interior range from the oldest rocks on Earth to modern seismic images of the inner core size. Ancient volcanic rocks can be associated with a depth and temperature of melting through their geochemical composition. Using this technique and some geological inferences about the conditions under which the rock is preserved, the temperature of the mantle can be inferred. The mantle itself is fully convective, so that the temperature in the mantle is basically constant with depth outside the top and bottom thermal boundary layers. This is not quite true because the temperature in any convective body under pressure must

neg: Structure of the Earth of iron–nickel alloy was subjected to the corelike pressures by gripping it in a vise between 2 diamond tips (diamond anvil cell), and then heating to approximately 4000 K. The sample was observed with x-rays, and strongly supported the theory that Earth's inner core was made of giant crystals running north to south. The liquid outer core surrounds the inner core and is believed to be composed of iron mixed with nickel and trace amounts of lighter elements. Recent speculation suggests that the innermost part of the core is enriched in gold, platinum and other siderophile elements. The matter that

neg: Giant-impact hypothesis noteworthy that the Earth has the highest density of all the planets in the Solar system; the absorption of the core of the impactor body explains this observation, given the proposed properties of the early Earth and Theia. Comparison of the zinc isotopic composition of Lunar samples with that of Earth and Mars rocks provides further evidence for the impact hypothesis. Zinc is strongly fractionated when volatilized in planetary rocks, but not during normal igneous processes, so zinc abundance and isotopic composition can distinguish the two geological processes. Moon rocks contain more heavy isotopes of zinc, and overall less zinc,

neg: Geochemistry Mg and Ca, dominate in the Earth's crust, forming silicates and other oxides. "Siderophile" elements (Fe, Co, Ni, Pt, Re, Os) have an affinity for iron and tend to concentrate in the core. "Chalcophile" elements (Cu, Ag, Zn, Pb, S) form sulfides; and "atmophile" elements (O, N, H and noble gases) dominate the atmosphere. Within each group, some elements are refractory, remaining stable at high temperatures, while others are volatile, evaporating more easily, so heating can separate them. The chemical composition of the Earth and other bodies is determined by two opposing processes: differentiation and mixing. In the Earth's mantle,

neg: Geochemical cycle As all closed systems, it follows the law of conservation of mass which states that matter cannot be created nor destroyed, thus, the matter, although transformed and migrated, remains the same as when the Earth was formed. The Earth system contains seven different reservoirs that are separated into surface reservoirs, which include atmosphere, hydrosphere, biosphere, pedosphere, and lithosphere and the isolated reservoirs that include deep Earth and outer space. Geochemical cycles are concerned with the interactions between deep earth which consists of Earth´s mantle and core, and the lithosphere which consists of the Earth´s crust. Flux in geochemical cycles is

neg: Earth trojan could be a rich source of such elements even if its overall composition is similar to Earth's; because of their small size, such bodies would lose heat much more rapidly than a planet once they had formed, and so would not have melted, a prerequisite for differentiation (even if they differentiated, the core would still be within reach). Their weak gravitational fields also would have inhibited significant separation of denser and lighter material; a mass the size of would exert a surface gravitational force of less than 0.00005 times that of Earth (although the asteroid's rotation could cause separation). A

neg: Surface features of Venus composition, Venus has a unique geology that is unlike Earth's. Although much older than Earth's, the surface of Venus is relatively young compared to other terrestrial planets (<500 million years old), possibly due to a global-scale resurfacing event that buried much of the previous rock record. Venus is believed to have approximately the same bulk elemental composition as Earth, due to the physical similarities, but the exact composition is unknown. The surface conditions on Venus are more extreme than on Earth, with temperatures ranging from 453 to 473 °C and pressures of 95 bar. Venus lacks water, which makes crustal

neg: Sample-return mission from 2011 to 2012 for imaging, and samples from HED meteorites (collected on Earth until then), which were compared to data gathered by Dawn. These meteorites could then be identified as material ejected from the large impact crater Rheasilvia on Vesta. This allowed deducing the composition of crust, mantle and core of Vesta. Similarly some differences in composition of asteroids (and, to a lesser extent, different compositions of comets) can be discerned by imaging alone. However, for a more precise inventory of the material on these different bodies, more samples will be collected and returned in the future, to match

neg: Primitive mantle this is the so-called D"-layer at the core-mantle boundary. The "Late veneer hypothesis" suggests that specific materials were added at the surface from extra external sources. There are arguments against this hypothesis Primitive mantle The primitive mantle is, in geochemistry, a hypothetical reservoir with the composition of the Earth's crust and mantle taken together. The currently accepted scientific hypothesis is that the Earth was formed by accretion of material with a chondritic composition. Still during the accretionary phase planetary differentiation started, giving rise to the Earth's core, where heavy metallic siderophile elements accumulated. Around it was a (in this stage)

neg: SKS wave hits the core-mantle boundary as it leaves the core, some energy is converted back to shear energy before the wave travels through the mantle. SKS waves can be observed by seismometers roughly 60-141° from an earthquake according to the Preliminary reference Earth model. SKS wave An SKS wave is a type of seismic wave, with the three letters denoting the type of wave-motion through the mantle and outer core. The first S indicates that the wave travels as a shear or s-wave through the mantle, the K shows that the wave travels as a compressional or p-wave through the outer

neg: European Project for Ice Coring in Antarctica configuration of the orbital parameters of the earth) to be an approximate analogue to the current interglacial, was quite long: 28 kyr. The Nature paper argues that if this analogue is accepted, the current climate would be expected to continue like today's, in the absence of human influence (which it states is unlikely, given the predicted increases in greenhouse gas concentrations). Further analysis of the core is hoped to extend the record back somewhat further, possibly as far as the Brunhes–Matuyama magnetic reversal, believed to be at about 780 kyr. The core "time scale" is derived from the measured depth

neg: Planet the Sun: Jupiter is the largest, at 318 Earth masses, whereas Mercury is the smallest, at 0.055 Earth masses. The planets of the Solar System can be divided into categories based on their composition: An exoplanet (extrasolar planet) is a planet outside the Solar System. In early 1992, radio astronomers Aleksander Wolszczan and Dale Frail announced the discovery of two planets orbiting the pulsar PSR 1257+12. This discovery was confirmed, and is generally considered to be the first definitive detection of exoplanets. These pulsar planets are believed to have formed from the unusual remnants of the supernova that produced the

neg: In situ resource utilization have return delta-v's from their surfaces to LEO which are less than the return from the Moon. Ceres is further out than Mars, with a higher delta-v, but launch windows and travel times are better, and the surface gravity is just 0.028 g, with a very low escape velocity of 510 m/s. Researchers have speculated that the interior configuration of Ceres includes a water-ice-rich mantle over a rocky core. Near Earth Asteroids and bodies in the asteroid belt could also be sources of raw materials for ISRU. Proposals have been made for "mining" for rocket propulsion, using what is called

neg: Seismic tomography better understand core, mantle, and plate tectonic processes. Tomography is solved as an inverse problem. Seismic travel time data are compared to an initial Earth model and the model is modified until the best possible fit between the model predictions and observed data is found. Seismic waves would travel in straight lines if Earth was of uniform composition, but the compositional layering, tectonic structure, and thermal variations reflect and refract seismic waves. The location and magnitude of these variations can be calculated by the inversion process, although solutions to tomographic inversions are non-unique. Seismic tomography is similar to medical x-ray

neg: Moon rock in hydrated minerals common in Earth rocks. In some regards, lunar rocks are closely related to Earth's rocks in their isotopic composition of the element oxygen. The Apollo moon rocks were collected using a variety of tools, including hammers, rakes, scoops, tongs, and core tubes. Most were photographed prior to collection to record the condition in which they were found. They were placed inside sample bags and then a "Special Environmental Sample Container" for return to the Earth to protect them from contamination. In contrast to the Earth, large portions of the lunar crust appear to be composed of rocks

neg: Allotropes of iron the solid parts of planetary cores. The inner core of the Earth is generally assumed to consist essentially of a crystalline iron-nickel alloy with ε structure. The outer core surrounding the solid inner core is believed to be composed of liquid iron mixed with nickel and trace amounts of lighter elements. As molten iron cools down, it solidifies at 1,538 °C (2,800 °F) into its δ allotrope, which has a body-centered cubic (BCC) crystal structure. δ-iron can dissolve as much as 0.08% of carbon by mass at 1,475 °C. As the iron cools further to 1,394 °C its crystal structure

neg: Seismic wave structures of the Earth interior. When an earthquake occurs, seismographs near the epicenter are able to record both P and S waves, but those at a greater distance no longer detect the high frequencies of the first S wave. Since shear waves cannot pass through liquids, this phenomenon was original evidence for the now well-established observation that the Earth has a liquid outer core, as demonstrated by Richard Dixon Oldham. This kind of observation has also been used to argue, by seismic testing, that the Moon has a solid core, although recent geodetic studies suggest the core is still molten.

neg: Brinsley Le Poer Trench, 8th Earl of Clancarty Earth had a liquid molten core'. According to Trench in his book "The Sky People", Adam and Eve, Noah any many of the other characters from the Bible originally lived on Mars. Trench believed that Adam and Eve were experiment creations of extraterrestrials. His claim was that the Biblical description of the Garden of Eden was inconsistent with what was on Earth and as Mars contained canals, that the Garden of Eden must have been located on Mars. He further claimed that the north polar ice cap melted on Mars, and this caused the descendants of Adam and Eve to

neg: Rotation and Interior Structure Experiment compared to Earth's. The mission launched on 5 May 2018 and landed on the surface of Mars at Elysium Planitia on 26 November 2018. The Principal Investigator for RISE is William Folkner of JPL, who led the 1997 investigation of Mars' core using the radio link between Earth and NASA's "Mars Pathfinder" (also included the "Sojourner" rover). RISE uses the spacecraft's radio connection with Earth to assess perturbations of Mars' rotation axis to within 10 centimeters. These measurements can provide information about the size and composition of Mars' core. The radio science equipment is largely the same as used for

neg: HD 219828 HD 219828 HD 219828 is an 8th magnitude star approximately 265 light years away in the constellation of Pegasus. It is a yellow subgiant, meaning that hydrogen fusion has ceased in its core. In 2007, a Neptune-mass planet was found orbiting the star by Melo. According to the author, assuming an Earth-like rocky composition, the planet could yield a radius 2.2 times that of Earth. This could be furtherly proved if transit were observed, though, as authors state, it is a difficult task. At this point, it was suggested that a best fit orbital solution hints the presence of an

neg: Lid tectonics lid tectonics. There are many characteristics of a planetary body that influence the presence and degree of lid tectonics. The temperature of a bodies core–mantle boundary, and the presence of water strongly effect the rheological, composition, and thermal diagnostics of lid tectonics. The lid will not participate in the underlying convection of the mantle. At the base of the lithosphere, where the lid is in contact with less viscous material, melts will form at the thermal boundary layer and cause drips, believed to be of peridotite composition. This stagnant lid regime will not effectively mix a mantle. Stagnant lid regime

neg: Core–mantle boundary Core–mantle boundary The core–mantle boundary (CMB in the parlance of solid earth geophysicists) of the Earth lies between the planet's silicate mantle and its liquid iron-nickel outer core. This boundary is located at approximately 2891 km (1796 mi) depth beneath the Earth's surface. The boundary is observed via the discontinuity in seismic wave velocities at that depth due to the differences between the acoustic impedances of the solid mantle and the molten outer core. P-wave velocities are much slower in the outer core than in the deep mantle while S-waves do not exist at all in the liquid portion of

neg: Terraforming of Venus some researchers, the Earth's mantle and/or core might hold large quantities of hydrogen left there since the original formation of Earth from the nebular cloud. Since the original formation and inner structure of Earth and Venus are generally believed to be somewhat similar, the same might be true for Venus. Iron aerosol in the atmosphere will also be required for the reaction to work, and iron can come from Mercury, asteroids, or the Moon. (Loss of hydrogen due to the solar wind is unlikely to be significant on the timescale of terraforming.) Due to the planet's relatively flat surface, this

neg: Geochemistry same composition as the Sun, but the planets could also have formed when a solid core captured nebular gas. In current models, the four giant planets have cores of rock and ice that are roughly the same size, but the proportion of hydrogen and helium decreases from about 300 Earth masses in Jupiter to 75 in Saturn and just a few in Uranus and Neptune. Thus, while the gas giants are primarily composed of hydrogen and helium, the ice giants are primarily composed of heavier elements (O, C, N, S), primarily in the form of water, methane and ammonia. The

neg: Broad-footed mole that run laterally and vertically up to the surface. The excess earth pushed out of these shafts form distinct volcano-shaped mounds with the older earth towards the outer base and the newer earth towards the core. Shallow surface tunnels are sometimes dug and form a ridge in the soil on the surface. How often exactly these tunnels are used is unknown seeing as they are used irregularly. Up to 12 subspecies of "S. latimanus" have been recognized, but a taxonomic revision published in 2004 recommended the southernmost subspecies, "S. l. anthonyi" (Anthony's Mexican mole) be elevated to full species, and

neg: History of Solar System formation and evolution hypotheses hot for water to condense), the similarity in composition (since the Moon had formed from part of the Earth), the lower density (since the Moon had formed from the Earth's crust and mantle, rather than its core), and the Moon's unusual orbit (since an oblique strike would have imparted a massive amount of angular momentum to the Earth–Moon system). However, the giant impact model has been criticised for being too explanatory; it can be expanded to explain any future discoveries and as such, is unfalsifiable. Also, many claim that much of the material from the impactor would have ended up

neg: Hapkeite Hapkeite Hapkeite is a mineral discovered in the Dhofar 280 meteorite found in 2000 in Oman on the Arabian peninsula. The meteorite is believed to originate from the Moon; specifically, it appears to be a fragment of lunar highland breccia. Hapkeite's composition is of silicon and iron, and it is similar to other silicon-iron minerals found on Earth. An impact on the Moon is thought to have launched the partially molten or vaporized material into orbit. Due to its 1:2 composition of silicon-iron, hapkeite was given the chemical formula FeSi. It occurs as opaque, yellowish to silvery microscopic isometric crystals.

neg: Planetary core dense than terrestrial planets) suggests that such planets like GJ1214b and GJ436 are composed of primarily water. Internal pressures of such water-worlds would result in exotic phases of water forming on the surface and within their cores. Planetary core The planetary core consists of the innermost layer(s) of a planet; which may be composed of solid and liquid layers. Cores of specific planets may be entirely solid or entirely liquid. In the Solar System, core size can range from about 20% (Moon) to 85% of a planet's radius (Mercury). Gas giants also have cores, though the composition of these are

neg: Crow religion God is to be properly respected. Yellowtail used Black Elk's description of the sacred pipe to demonstrate what he believed to be the importance of scared pipe to Crows. "With this sacred pipe you will walk upon the Earth; for the Earth is your Grandmother and Mother, and she is sacred. Every step that has been taken upon Her should be as a prayer. The bowl of this pipe is of red stone; it is the Earth… The stem of this pipe is of wood, and this represents all that grows upon Earth… all things of the universe are joined

neg: Northwest Africa 7325 a primitive achondrite. Notable for its green fusion crust and high-magnesium/low-iron composition, NWA 7325 is estimated to be 4.56 billion years old and was likely ejected from Mercury on an Earth-intersecting trajectory by an impact. Northwest Africa 7325 Northwest Africa 7325, also known as NWA 7325 is the first meteorite believed to have originated from Mercury. Found in a marketplace in Erfoud, Morocco in April 2012, the meteorite is composed of 35 fragments with a combined weight of approximately . Investigation of the meteorite by Anthony Irving at the University of Washington determined that the meteorite's composition is consistent with

neg: Abiogenic petroleum origin primordial origin. Meteorites are believed to represent the major composition of material from which the Earth was formed. Some meteorites, such as carbonaceous chondrites, contain carbonaceous material. If a large amount of this material is still within the Earth, it could have been leaking upward for billions of years. The thermodynamic conditions within the mantle would allow many hydrocarbon molecules to be at equilibrium under high pressure and high temperature. Although molecules in these conditions may disassociate, resulting fragments would be reformed due to the pressure. An average equilibrium of various molecules would exist depending upon conditions and the carbon-hydrogen

neg: Jupiter rocky, but its detailed composition is unknown, as are the properties of materials at the temperatures and pressures of those depths (see below). In 1997, the existence of the core was suggested by gravitational measurements, indicating a mass of from 12 to 45 times that of Earth, or roughly 4%–14% of the total mass of Jupiter. The presence of a core during at least part of Jupiter's history is suggested by models of planetary formation that require the formation of a rocky or icy core massive enough to collect its bulk of hydrogen and helium from the protosolar nebula. Assuming

neg: Volcanology of Mars of years. The authors consider this age makes it possible that Mars is not yet volcanically extinct. The upcoming "InSight" lander mission will determine if there is any seismic activity, measure the amount of heat flow from the interior, estimate the size of Mars' core and whether the core is liquid or solid. Large amounts of water ice are believed to be present in the Martian subsurface. The interaction of ice with molten rock can produce distinct landforms. On Earth, when hot volcanic material comes into contact with surface ice, large amounts of liquid water and mud may form that

neg: Earth's magnetic field towards Siberia with a presently accelerating rate— per year at the beginning of the 20th century, up to per year in 2003, and since then has only accelerated. The Earth's magnetic field is believed to be generated by electric currents in the conductive material of its core, created by convection currents due to heat escaping from the core. However the process is complex, and computer models that reproduce some of its features have only been developed in the last few decades. The Earth and most of the planets in the Solar System, as well as the Sun and other stars,

neg: Alkali metal matter that formed the Sun, but the planets acquired different compositions during the formation and evolution of the solar system. In turn, the natural history of the Earth caused parts of this planet to have differing concentrations of the elements. The mass of the Earth is approximately 5.98 kg. It is composed mostly of iron (32.1%), oxygen (30.1%), silicon (15.1%), magnesium (13.9%), sulfur (2.9%), nickel (1.8%), calcium (1.5%), and aluminium (1.4%); with the remaining 1.2% consisting of trace amounts of other elements. Due to planetary differentiation, the core region is believed to be primarily composed of iron (88.8%), with smaller

neg: Terra Sirenum time. A magnetic field of a planet is believed to be caused by fluid motions under the surface. However, there are some differences, between the magnetic stripes on Earth and those on Mars. The Martian stripes are wider, much more strongly magnetized, and do not appear to spread out from a middle crustal spreading zone. Because the area containing the magnetic stripes is about 4 billion years old, it is believed that the global magnetic field probably lasted for only the first few hundred million years of Mars' life, when the temperature of the molten iron in the planet's core

neg: Ross 128 b been observed. Ross 128 b would be (Earth radii) for a pure-iron composition and 3.0 for a pure hydrogen-helium composition, both implausible extremes. For a more plausible Earth-like composition, the planet would need to be about - i.e., 1.1 times the radius of Earth (approximately ). With that radius, Ross 128 b would be slightly denser than Earth, due to how a rocky planet would become more compact as it increases in size. It would give the planet a gravitational pull around , or about 1.12 times that of Earth. Ross 128 b is calculated to have a temperature similar

neg: Silicon abundances are not replicated well on Earth due to substantial separation of the elements taking place during the formation of the Solar System. Silicon makes up 27.2% of the Earth's crust by weight, second only to oxygen at 45.5%, with which it always is associated in nature. Further fractionation took place in the formation of the Earth by planetary differentiation: Earth's core, which makes up 31.5% of the mass of the Earth, has approximate composition FeNiCoS; the mantle makes up 68.1% of the Earth's mass and is composed mostly of denser oxides and silicates, an example being olivine, (Mg,Fe)SiO; while

neg: Absurdity theory that reason and faith may be hostile to each other. The statement ""Credo quia absurdum"" ("I believe because it is absurd") is attributed to Tertullian from "De Carne Christi", as translated by philosopher Voltaire. According to the New Advent Church, what Tertullian actually says in DCC 5 is "... the Son of God died; it is by all means to be believed, because it is absurd." In the 15th century, the Spanish theologian Tostatus used what he thought was a reduction to absurdity arguing against a spherical earth using dogma, arguing that a spherical earth would imply the existence

neg: Confidence she does not have a personal certainty belief that s/he can handle what it takes or what needs to be done. Stajkovic (2006) argues that all three – skill, will, and confidence – are needed for action to unfold. The opposite of confidence is doubt. Alexander Stajkovic argues that confidence is not actually an observable variable, however, confidence sits at the core of four other manifestations: Hope, Efficacy, Optimism and Resilience. Core confidence impacts hope by allowing one to figure out what needs to be done and how to do it. It affects self-efficacy as one gains the belief that

neg: Evolutionary history of life lead deposits, has put the estimated age of Earth at around that time. The Moon has the same composition as Earth's crust but does not contain an iron-rich core like the Earth's. Many scientists think that about 40 million years after the formation of Earth, it collided with a body the size of Mars, throwing into orbit crust material that formed the Moon. Another hypothesis is that the Earth and Moon started to coalesce at the same time but the Earth, having much stronger gravity than the early Moon, attracted almost all the iron particles in the area. Until 2001,

neg: Astrophysical X-ray source its core. A Chandra X-ray image of Sirius A and B shows Sirius B to be more luminous than Sirius A. Whereas in the visual range, Sirius A is the more luminous. Regarding Cassiopea A SNR, it is believed that first light from the stellar explosion reached Earth approximately 300 years ago but there are no historical records of any sightings of the progenitor supernova, probably due to interstellar dust absorbing optical wavelength radiation before it reached Earth (although it is possible that it was recorded as a sixth magnitude star 3 Cassiopeiae by John Flamsteed on August 16, 1680).

neg: Starhaven Starhaven Starhaven is a fictional planet first depicted in stories of DC Comics' Legion of Super-Heroes set in the 30th and 31st Centuries, and described as being located near the core of the Milky Way galaxy. It was portrayed as being the home of Legion member Dawnstar and R.E.B.E.L.S. member Wildstar. Starhaven was described as being forcibly settled in the 13th Century by the Anasazi tribe, believed on Earth to be extinct. As a result of genetic engineering by the same unknown alien race which abducted them from Earth, their metagenes were said to have been triggered to cause specific

neg: Psyche (spacecraft) Psyche (spacecraft) Psyche is a planned orbiter mission that will explore the origin of planetary cores by studying the metallic asteroid . Lindy Elkins-Tanton of Arizona State University is the Principal Investigator who proposed this mission for NASA's Discovery Program. NASA's Jet Propulsion Laboratory (JPL) will manage the project. 16 Psyche is the heaviest known M-type asteroid, and is thought to be the exposed iron core of a protoplanet. This asteroid may be the remnant of a violent collision with another object that stripped off the outer crust. Radar observations of the asteroid from Earth indicate an iron–nickel composition. On

neg: Geology of Venus the oldest parts of the planet. It was once thought that the tesserae were continents associated with tectonic plates like those of the Earth; in reality they are probably the result of floods of basaltic lava forming large plains, which were then subjected to intense tectonic fracturing. Venus's crust appears to be thick, and composed of silicate rocks. Venus's mantle is approximately thick, its chemical composition is probably similar to that of chondrites. Since Venus is a terrestrial planet, it is presumed to have a core made of semisolid iron and nickel with a radius of approximately . The unavailability

neg: Foundationism Foundationism Foundationism is a fictional religion in depicted in the 1993 – 1998 American science fiction television series "Babylon 5". It is presented as an Earth religion, one of several that appeared around the time the Centauri aliens made first contact with the humans of the Earth Alliance in 2156. The intent behind the new religion was to get back to the roots of all Earth religions, past disparate doctrines to the core foundations of each belief system to find out what they have in common, proposing that they are more similar than might be expected. It further asserted that

neg: Cosmochemistry what they called "cosmic abundances" based on their analysis of several terrestrial and meteorite samples. Goldschmidt justified the inclusion of meteorite composition data into his table by claiming that terrestrial rocks were subjected to a significant amount of chemical change due to the inherent processes of the Earth and the atmosphere. This meant that studying terrestrial rocks exclusively would not yield an accurate overall picture of the chemical composition of the cosmos. Therefore, Goldschmidt concluded that extraterrestrial material must also be included to produce more accurate and robust data. This research is considered to be the foundation of modern cosmochemistry.

neg: Poseidon horse, and this is evident by his cult in Peloponnesos. However he was originally a god of the waters, and therefore he became the "earth-shaker", because the Greeks believed that the cause of the earthquakes was the erosion of the rocks by the waters, by the rivers who they saw to disappear into the earth and then to burst out again. This is what the natural philosophers Thales, Anaximenes and Aristotle believed, which could not be different from the folklore belief. Later, when the Myceneans travelled along the sea, he was assigned a role as god of the sea. In

neg: Main Core Main Core Main Core is the code name of an American governmental database that is believed to have been in existence since the 1980s. It is believed that Main Core is a federal database containing personal and financial data of millions of United States citizens believed to be threats to national security. The data, which is believed to come from the NSA, FBI, CIA, and other sources, is collected and stored without warrants or court orders. The database's name derives from the fact that it contains "copies of the 'main core' or essence of each item of intelligence information on

neg: Seven Coloured Earths the decomposition of volcanic rock (basalt) gullies into clay, further transformed into ferralitic soil by total hydrolysis; the two main elements of the resulting soil, iron and aluminium, are responsible for red/anthracite and blue/purplish colours respectively. The different shades of colour are believed to be a consequence of the molten volcanic rock cooling down at different external temperatures (hence rates), but the causes of their consistent spontaneous separation are yet to be fully clarified. The name "Seven Coloured Earth(s)" is a descriptive—rather than an official—name. Sources report many variations of this name, including "Chamarel Seven Coloured Earths", "Chamarel Coloured Earth(s)",

neg: Isotopes of sulfur with a distinctive isotopic composition has been used to identify pollution sources, and enriched sulfur has been added as a tracer in hydrologic studies. Differences in the natural abundances can also be used in systems where there is sufficient variation in the S of ecosystem components. Rocky Mountain lakes thought to be dominated by atmospheric sources of sulfate have been found to have different δS-34 values from oceans believed to be dominated by watershed sources of sulfate. Isotopes of sulfur Sulfur (S) has 24 known isotopes with mass numbers ranging from 26 to 49, four of which are stable: S

neg: (6178) 1986 DA tons of iron and a billion tons of nickel." In 2012 the estimated value of 100,000 tons of platinum was worth approximately five trillion US dollars. The delta-v for a spacecraft rendezvous with this asteroid from low earth orbit is 7.1 km/s. (6178) 1986 DA 1986 DA was the first near Earth asteroid thought to be of metallic composition, with high radar brightness; with that it was predicted to have 100 thousand tons of platinum group metals including gold and suggested as a resource for future space colonists. As an eccentric Amor asteroid has an Earth minimum orbit intersection distance

neg: Principle of compositionality decades before Frege's work. The principle of compositionality states that in a meaningful sentence, if the lexical parts are taken out of the sentence, what remains will be the rules of composition. Take, for example, the sentence "Socrates was a man". Once the meaningful lexical items are taken away—"Socrates" and "man"—what is left is the pseudo-sentence, "S was a M". The task becomes a matter of describing what the connection is between S and M. It is frequently taken to mean that every operation of the syntax should be associated with an operation of the semantics that acts on the

neg: Geology much more detailed view of the interior of the Earth, and have replaced the simplified layered model with a much more dynamic model. Mineralogists have been able to use the pressure and temperature data from the seismic and modelling studies alongside knowledge of the elemental composition of the Earth to reproduce these conditions in experimental settings and measure changes in crystal structure. These studies explain the chemical changes associated with the major seismic discontinuities in the mantle and show the crystallographic structures expected in the inner core of the Earth. The geologic time scale encompasses the history of the Earth.

neg: Christian Identity instead believed that the flood was only local and that the Earth was billions of years old. Christian Identity adherents claim that the flood in Genesis only rose high enough to drown the region of the Tarim Basin below sea level (Gen. 7:20) and that therefore the Hebrew word "eretz" which appears in those verses should be rendered "the land" (as in a specific place) rather than "the earth." Racialism, or race-based philosophy, is the core tenet of Christian Identity, and most CI adherents are white nationalists who support racial segregation. Some CI adherents believe that Jews are genetically compelled

neg: Edgar Allan Poe He disliked didacticism and allegory, though he believed that meaning in literature should be an undercurrent just beneath the surface. Works with obvious meanings, he wrote, cease to be art. He believed that work of quality should be brief and focus on a specific single effect. To that end, he believed that the writer should carefully calculate every sentiment and idea. Poe describes his method in writing "The Raven" in the essay "The Philosophy of Composition", and he claims to have strictly followed this method. It has been questioned whether he really followed this system, however. T. S. Eliot said:

neg: Earth Run Wave". Earth Run Earth Run is a studio album by jazz guitarist Lee Ritenour that was released in 1986 by GRP Records. The album got to No. 10 on the Billboard Jazz Albums chart. As an album, "Earth Run" was nominated for a Grammy Award for Best jazz fusion performance, vocal or instrumental. The title cut also got a separate nomination for Best Instrumental Composition. The third track, "If I'm Dreamin' (Don't Wake Me)", was sampled by French house DJ Fred Falke in three of his songs: 2009's "When I Look Into Your Eyes" and "Back to Stay", and 2011's

neg: Earth Run Earth Run Earth Run is a studio album by jazz guitarist Lee Ritenour that was released in 1986 by GRP Records. The album got to No. 10 on the Billboard Jazz Albums chart. As an album, "Earth Run" was nominated for a Grammy Award for Best jazz fusion performance, vocal or instrumental. The title cut also got a separate nomination for Best Instrumental Composition. The third track, "If I'm Dreamin' (Don't Wake Me)", was sampled by French house DJ Fred Falke in three of his songs: 2009's "When I Look Into Your Eyes" and "Back to Stay", and 2011's "Last