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53-410: The nebula holds about 0.13 solar masses ( M ☉ ) of matter, including hydrogen, helium, nitrogen, oxygen, and sulfur; all with a density of less than 100 particles per cubic centimeter. Its outer radius is around 0.91 ly (0.28 pc) and it is expanding with velocities in the range of 27–39 km/s into the surrounding interstellar medium . The 14th magnitude central star has passed

106-463: A planetary nebula . When William Parsons, 3rd Earl of Rosse , observed the nebula in Ireland in 1848, his hand-drawn illustration resembled an owl 's head. In his notes, the object was described as "Two stars considerably apart in the central region, dark penumbra round each spiral arrangement, with stars as apparent centres of attraction. Stars sparkling in it; resolvable." It has been known as

159-544: A 1749 paper that they had been able to detect a deflection of 8  seconds of arc , the accuracy was not enough for a definite estimate on the mean density of the Earth, but Bouguer stated that it was at least sufficient to prove that the Earth was not hollow . That a further attempt should be made on the experiment was proposed to the Royal Society in 1772 by Nevil Maskelyne , Astronomer Royal . He suggested that

212-399: A suitable mountain. After a lengthy search over the summer of 1773, Mason reported that the best candidate was Schiehallion , a peak in the central Scottish Highlands . The mountain stood in isolation from any nearby hills, which would reduce their gravitational influence, and its symmetrical east–west ridge would simplify the calculations. Its steep northern and southern slopes would allow

265-531: A telescope with an aperture 10" or better is required. To locate the nebula in the night sky, look to the southwest corner of the Big Dipper 's bowl, marked by the star Beta Ursae Majoris . From there, M97 lies just over 2.5 degrees in the southeast direction towards the star positioned opposite Beta Ursae Majoris in the other bottom corner of the Big Dippers Bowl, Gamma Ursae Majoris ; which marks

318-399: A total mass of the order of 10  kg . Isaac Newton estimated, without access to reliable measurement, that the density of Earth would be five or six times as great as the density of water, which is surprisingly accurate (the modern value is 5.515). Newton under-estimated the Earth's volume by about 30%, so that his estimate would be roughly equivalent to (4.2 ± 0.5) × 10  kg . In

371-592: A unit of measurement, the solar mass came into use before the AU and the gravitational constant were precisely measured. This is because the relative mass of another planet in the Solar System or the combined mass of two binary stars can be calculated in units of Solar mass directly from the orbital radius and orbital period of the planet or stars using Kepler's third law. The mass of the Sun cannot be measured directly, and

424-410: Is converted into helium through nuclear fusion , in particular the p–p chain , and this reaction converts some mass into energy in the form of gamma ray photons. Most of this energy eventually radiates away from the Sun. Second, high-energy protons and electrons in the atmosphere of the Sun are ejected directly into outer space as the solar wind and coronal mass ejections . The original mass of

477-461: Is difficult to measure and is only known with limited accuracy ( see Cavendish experiment ). The value of G times the mass of an object, called the standard gravitational parameter , is known for the Sun and several planets to a much higher accuracy than G alone. As a result, the solar mass is used as the standard mass in the astronomical system of units . The Sun is losing mass because of fusion reactions occurring within its core, leading to

530-412: Is equivalent to an average density of 5515 kg/m . Using the nearest metric prefix , the Earth mass is approximately six ronnagrams , or 6.0 Rg. The Earth mass is a standard unit of mass in astronomy that is used to indicate the masses of other planets , including rocky terrestrial planets and exoplanets . One Solar mass is close to 333 000 Earth masses. The Earth mass excludes

583-530: Is estimated to be: which can be expressed in terms of solar mass as: The ratio of Earth mass to lunar mass has been measured to great accuracy. The current best estimate is: The product of M E and the universal gravitational constant ( G ) is known as the geocentric gravitational constant ( G M E ) and equals (398 600 441 .8 ± 0.8) × 10  m s . It is determined using laser ranging data from Earth-orbiting satellites, such as LAGEOS-1 . G M E can also be calculated by observing

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636-689: Is instead calculated from other measurable factors, using the equation for the orbital period of a small body orbiting a central mass. Based on the length of the year, the distance from Earth to the Sun (an astronomical unit or AU), and the gravitational constant ( G ), the mass of the Sun is given by solving Kepler's third law : M ⊙ = 4 π 2 × ( 1 A U ) 3 G × ( 1 y r ) 2 {\displaystyle M_{\odot }={\frac {4\pi ^{2}\times (1\,\mathrm {AU} )^{3}}{G\times (1\,\mathrm {yr} )^{2}}}} The value of G

689-402: Is notoriously difficult to measure, and some high-precision measurements during the 1980s to 2010s have yielded mutually exclusive results. Sagitov (1969) based on the measurement of G by Heyl and Chrzanowski (1942) cited a value of M E = 5.973(3) × 10  kg (relative uncertainty 5 × 10 ). Accuracy has improved only slightly since then. Most modern measurements are repetitions of

742-530: Is variable, subject to both gain and loss due to the accretion of in-falling material, including micrometeorites and cosmic dust and the loss of hydrogen and helium gas, respectively. The combined effect is a net loss of material, estimated at 5.5 × 10  kg (5.4 × 10 long tons ) per year. This amount is 10 of the total earth mass. The 5.5 × 10  kg annual net loss is essentially due to 100,000 tons lost due to atmospheric escape , and an average of 45,000 tons gained from in-falling dust and meteorites. This

795-401: Is well within the mass uncertainty of 0.01% ( 6 × 10  kg ), so the estimated value of Earth's mass is unaffected by this factor. Mass loss is due to atmospheric escape of gases. About 95,000 tons of hydrogen per year ( 3 kg/s ) and 1,600 tons of helium per year are lost through atmospheric escape. The main factor in mass gain is in-falling material, cosmic dust , meteors , etc. are

848-448: The asymptotic giant branch , before peaking at a rate of 10 to 10 M ☉ /year as the Sun generates a planetary nebula . By the time the Sun becomes a degenerate white dwarf , it will have lost 46% of its starting mass. The mass of the Sun has been decreasing since the time it formed. This occurs through two processes in nearly equal amounts. First, in the Sun's core , hydrogen

901-445: The atmosphere for about one part per million . The mass of Earth is measured indirectly by determining other quantities such as Earth's density, gravity, or gravitational constant. The first measurement in the 1770s Schiehallion experiment resulted in a value about 20% too low. The Cavendish experiment of 1798 found the correct value within 1%. Uncertainty was reduced to about 0.2% by the 1890s, to 0.1% by 1930. The figure of

954-515: The gravitational constant , which is the fundamental physical constant known with least accuracy, due to the relative weakness of the gravitational force . The mass of the Earth was first measured with any accuracy (within about 20% of the correct value) in the Schiehallion experiment in the 1770s, and within 1% of the modern value in the Cavendish experiment of 1798. The mass of Earth

1007-416: The mass–energy equivalence principle , although these changes are relatively negligible. Mass loss due to the combination of nuclear fission and natural radioactive decay is estimated to amount to 16 tons per year. An additional loss due to spacecraft on escape trajectories has been estimated at 65 tons per year since the mid-20th century. Earth lost about 3473 tons in the initial 53 years of

1060-401: The 18th century, knowledge of Newton's law of universal gravitation permitted indirect estimates on the mean density of the Earth, via estimates of (what in modern terminology is known as) the gravitational constant . Early estimates on the mean density of the Earth were made by observing the slight deflection of a pendulum near a mountain, as in the Schiehallion experiment . Newton considered

1113-559: The Cavendish experiment, and the modern value of G (and hence, of the Earth mass) is still derived from high-precision repetitions of the Cavendish experiment. In 1821, Francesco Carlini determined a density value of ρ = 4.39 g/cm through measurements made with pendulums in the Milan area. This value was refined in 1827 by Edward Sabine to 4.77 g/cm , and then in 1841 by Carlo Ignazio Giulio to 4.95 g/cm . On

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1166-478: The Cavendish experiment, with results (within standard uncertainty) ranging between 6.672 and 6.676 × 10  m /kg/s (relative uncertainty 3 × 10 ) in results reported since the 1980s, although the 2014 CODATA recommended value is close to 6.674 × 10  m /kg/s with a relative uncertainty below 10 . The Astronomical Almanach Online as of 2016 recommends a standard uncertainty of 1 × 10 for Earth mass, M E 5.9722(6) × 10  kg Earth's mass

1219-417: The Earth has been known to better than four significant digits since the 1960s ( WGS66 ), so that since that time, the uncertainty of the Earth mass is determined essentially by the uncertainty in measuring the gravitational constant . Relative uncertainty was cited at 0.06% in the 1970s, and at 0.01% (10 ) by the 2000s. The current relative uncertainty of 10 amounts to 6 × 10  kg in absolute terms, of

1272-417: The Earth had a spherical stratification. Later, in 1883, the experiments conducted by Robert von Sterneck (1839 to 1910) at different depths in mines of Saxony and Bohemia provided the average density values ρ between 5.0 and 6.3 g/cm . This led to the concept of isostasy, which limits the ability to accurately measure ρ , by either the deviation from vertical of a plumb line or using pendulums. Despite

1325-482: The Encyclopaedia Britannica (Vol. 25, 1902) with a "logarithm of earth's mass" given as "14.600522" [ 3.985 86 × 10 ]. This is the gravitational parameter in m ·s (modern value 3.986 00 × 10 ) and not the absolute mass. Experiments involving pendulums continued to be performed in the first half of the 19th century. By the second half of the century, these were outperformed by repetitions of

1378-465: The IAU Division I Working Group, has the following estimates: Earth mass An Earth mass (denoted as M 🜨 , M ♁ or M E , where 🜨 and ♁ are the astronomical symbols for Earth ), is a unit of mass equal to the mass of the planet Earth . The current best estimate for the mass of Earth is M 🜨 = 5.9722 × 10  kg , with a relative uncertainty of 10 . It

1431-495: The Owl Nebula ever since. More recent developments in the late 1900s include the discovery of a giant red halo of wind extended around its inner shells, and the mapping of the nebula's structure. Although the Owl Nebula can not be seen with the naked eye, a faint image of it can be observed under remarkably good conditions with a small telescope or 20×80 binoculars. To make out the nebula's more distinctive owl like eye features,

1484-477: The Sun at the time it reached the main sequence remains uncertain. The early Sun had much higher mass-loss rates than at present, and it may have lost anywhere from 1–7% of its natal mass over the course of its main-sequence lifetime. One solar mass, M ☉ , can be converted to related units: It is also frequently useful in general relativity to express mass in units of length or time. The solar mass parameter ( G · M ☉ ), as listed by

1537-408: The Sun was accurately measured during the transits of Venus in 1761 and 1769, yielding a value of 9″ (9  arcseconds , compared to the present value of 8.794 148 ″ ). From the value of the diurnal parallax, one can determine the distance to the Sun from the geometry of Earth. The first known estimate of the solar mass was by Isaac Newton . In his work Principia (1687), he estimated that

1590-451: The absolute numbers would have been too awkward. Ritchie (1850) gives the mass of the Earth's atmosphere as "11,456,688,186,392,473,000 lbs". ( 1.1 × 10  lb = 5.0 × 10  kg , modern value is 5.15 × 10  kg ) and states that "compared with the weight of the globe this mighty sum dwindles to insignificance". Absolute figures for the mass of the Earth are cited only beginning in

1643-456: The constellations southwest corner. M97, together with Alpha Ursae Majoris , point the way to Polaris . Solar mass The solar mass ( M ☉ ) is a standard unit of mass in astronomy , equal to approximately 2 × 10   kg . It is approximately equal to the mass of the Sun . It is often used to indicate the masses of other stars , as well as stellar clusters , nebulae , galaxies and black holes . More precisely,

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1696-447: The degree of latitude, corresponding to a radius of 5500 km (86% of the Earth's actual radius of about 6371 km ), resulting in an estimated volume of about one third smaller than the correct value. The average density of the Earth was not accurately known. Earth was assumed to consist either mostly of water ( Neptunism ) or mostly of igneous rock ( Plutonism ), both suggesting average densities far too low, consistent with

1749-426: The densities of the major Solar System objects in relative terms. Henry Cavendish (1798) was the first to attempt to measure the gravitational attraction between two bodies directly in the laboratory. Earth's mass could be then found by combining two equations; Newton's second law , and Newton's law of universal gravitation . In modern notation, the mass of the Earth is derived from the gravitational constant and

1802-404: The emission of electromagnetic energy , neutrinos and by the ejection of matter with the solar wind . It is expelling about (2–3) × 10   M ☉ /year. The mass loss rate will increase when the Sun enters the red giant stage, climbing to (7–9) × 10   M ☉ /year when it reaches the tip of the red-giant branch . This will rise to 10   M ☉ /year on

1855-584: The experiment in Principia , but pessimistically concluded that the effect would be too small to be measurable. An expedition from 1737 to 1740 by Pierre Bouguer and Charles Marie de La Condamine attempted to determine the density of Earth by measuring the period of a pendulum (and therefore the strength of gravity) as a function of elevation. The experiments were carried out in Ecuador and Peru, on Pichincha Volcano and mount Chimborazo . Bouguer wrote in

1908-463: The experiment to be sited close to its centre of mass , maximising the deflection effect. Nevil Maskelyne , Charles Hutton and Reuben Burrow performed the experiment, completed by 1776. Hutton (1778) reported that the mean density of the Earth was estimated at ⁠ 9 / 5 ⁠ that of Schiehallion mountain. This corresponds to a mean density about 4 + 1 ⁄ 2 higher than that of water (i.e., about 4.5 g/cm ), about 20% below

1961-701: The experiment would "do honour to the nation where it was made" and proposed Whernside in Yorkshire , or the Blencathra - Skiddaw massif in Cumberland as suitable targets. The Royal Society formed the Committee of Attraction to consider the matter, appointing Maskelyne, Joseph Banks and Benjamin Franklin amongst its members. The Committee despatched the astronomer and surveyor Charles Mason to find

2014-519: The little chance of an accurate estimate of the average density of the Earth in this way, Thomas Corwin Mendenhall in 1880 realized a gravimetry experiment in Tokyo and at the top of Mount Fuji . The result was ρ = 5.77 g/cm . The uncertainty in the modern value for the Earth's mass has been entirely due to the uncertainty in the gravitational constant G since at least the 1960s. G

2067-566: The mass of the Moon . The mass of the Moon is about 1.2% of that of the Earth, so that the mass of the Earth–Moon system is close to 6.0457 × 10  kg . Most of the mass is accounted for by iron and oxygen (c. 32% each), magnesium and silicon (c. 15% each), calcium , aluminium and nickel (c. 1.5% each). Precise measurement of the Earth mass is difficult, as it is equivalent to measuring

2120-415: The mass of the Sun is The solar mass is about 333 000 times the mass of Earth ( M E ), or 1047 times the mass of Jupiter ( M J ). The value of the gravitational constant was first derived from measurements that were made by Henry Cavendish in 1798 with a torsion balance . The value he obtained differs by only 1% from the modern value, but was not as precise. The diurnal parallax of

2173-661: The mass, the mantle for 84% of the volume and close to 70% of the mass, while the crust accounts for less than 1% of the mass. About 90% of the mass of the Earth is composed of the iron–nickel alloy (95% iron) in the core (30%), and the silicon dioxides (c. 33%) and magnesium oxide (c. 27%) in the mantle and crust. Minor contributions are from iron(II) oxide (5%), aluminium oxide (3%) and calcium oxide (2%), besides numerous trace elements (in elementary terms: iron and oxygen c. 32% each, magnesium and silicon c. 15% each, calcium , aluminium and nickel c. 1.5% each). Carbon accounts for 0.03%, water for 0.02%, and

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2226-405: The mean Earth radius by Where gravity of Earth , "little g", is Cavendish found a mean density of 5.45 g/cm , about 1% below the modern value. While the mass of the Earth is implied by stating the Earth's radius and density, it was not usual to state the absolute mass explicitly prior to the introduction of scientific notation using powers of 10 in the later 19th century, because

2279-467: The micrometer wires: its light is faint, without a star. M. Méchain saw it the first time on Feb 16, 1781, & the position is that given by him. Near this nebula he has seen another one, [the position of] which has not yet been determined [Messier 108] , and also a third which is near Gamma of the Great Bear [Messier 109] . (diam. 2′). In 1844, Admiral William H. Smyth classified the object as

2332-503: The modern value, but still significantly larger than the mean density of normal rock, suggesting for the first time that the interior of the Earth might be substantially composed of metal. Hutton estimated this metallic portion to occupy some ⁠ 20 / 31 ⁠ (or 65%) of the diameter of the Earth (modern value 55%). With a value for the mean density of the Earth, Hutton was able to set some values to Jérôme Lalande 's planetary tables, which had previously only been able to express

2385-478: The most significant contributors to Earth's increase in mass. The sum of material is estimated to be 37 000 to 78 000  tons annually, although this can vary significantly; to take an extreme example, the Chicxulub impactor , with a midpoint mass estimate of 2.3 × 10  kg , added 900 million times that annual dustfall amount to the Earth's mass in a single event. Additional changes in mass are due to

2438-459: The motion of the Moon or the period of a pendulum at various elevations, although these methods are less precise than observations of artificial satellites. The relative uncertainty of G M E is just 2 × 10 , considerably smaller than the relative uncertainty for M E itself. M E can be found out only by dividing G M E by G , and G is known only to a relative uncertainty of 2.2 × 10 , so M E will have

2491-401: The order of the mass of a minor planet (70% of the mass of Ceres ). Before the direct measurement of the gravitational constant , estimates of the Earth mass were limited to estimating Earth's mean density from observation of the crust and estimates on Earth's volume. Estimates on the volume of the Earth in the 17th century were based on a circumference estimate of 60 miles (97 km) to

2544-540: The other hand, George Biddell Airy sought to determine ρ by measuring the difference in the period of a pendulum between the surface and the bottom of a mine. The first tests and experiments took place in Cornwall between 1826 and 1828. The experiment was a failure due to a fire and a flood. Finally, in 1854, Airy got the value 6.6 g/cm by measurements in a coal mine in Harton, Sunderland. Airy's method assumed that

2597-504: The ratio of the mass of Earth to the Sun was about 1 ⁄ 28 700 . Later he determined that his value was based upon a faulty value for the solar parallax, which he had used to estimate the distance to the Sun. He corrected his estimated ratio to 1 ⁄ 169 282 in the third edition of the Principia . The current value for the solar parallax is smaller still, yielding an estimated mass ratio of 1 ⁄ 332 946 . As

2650-481: The same uncertainty at best. For this reason and others, astronomers prefer to use G M E , or mass ratios (masses expressed in units of Earth mass or Solar mass ) rather than mass in kilograms when referencing and comparing planetary objects. Earth's density varies considerably, between less than 2700 kg/m in the upper crust to as much as 13 000  kg/m in the inner core . The Earth's core accounts for 15% of Earth's volume but more than 30% of

2703-539: The second half of the 19th century, mostly in popular rather than expert literature. An early such figure was given as "14 septillion pounds" ( 14 Quadrillionen Pfund ) [ 6.5 × 10  kg ] in Masius (1859). Beckett (1871) cites the "weight of the earth" as "5842 quintillion tons " [ 5.936 × 10  kg ]. The "mass of the earth in gravitational measure" is stated as "9.81996×6370980 " in The New Volumes of

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2756-486: The turning point in its evolution and is condensing to form a white dwarf . It has 55–60% of solar mass, is 41 to 148 times solar luminosity ( L ☉ ), and has an effective temperature of 123,000 K. The star has been successfully resolved by the Spitzer Space Telescope as a point source that does not show the infrared excess characteristic of a circumstellar disk . The Owl Nebula

2809-460: Was discovered by French astronomer Pierre Méchain on February 16, 1781. Pierre Méchain was Charles Messier's observing colleague, and the nebula was observed by Messier himself a few weeks following the initial sighting. Thus, the object was named Messier 97, and included in his catalog on March 24, 1781. Of the object, he noted: Nebula in the great Bear , near Beta: It is difficult to see, reports M. Méchain , especially when one illuminates

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