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113-629: The Blue Marble is a photograph of Earth taken on December 7, 1972, by either Ron Evans or Harrison Schmitt aboard the Apollo 17 spacecraft on its way to the Moon . Viewed from around 29,400 km (18,300 mi) from Earth's surface, a cropped and rotated version has become one of the most reproduced images in history. In the original NASA image, named AS17-148-22727 and centered at about 26°19′49″S 37°25′13″E  /  26.33028°S 37.42028°E  / -26.33028; 37.42028 with

226-540: A circumstellar disk , and then the planets grow out of that disk with the Sun. A nebula contains gas, ice grains, and dust (including primordial nuclides ). According to nebular theory , planetesimals formed by accretion , with the primordial Earth being estimated as likely taking anywhere from 70 to 100 million years to form. Estimates of the age of the Moon range from 4.5 Ga to significantly younger. A leading hypothesis

339-513: A "psychedelic illusion" of the Earth's curvature, convincing him that a picture of the entire planet would change how humans related to it. He sold and distributed buttons for 25 cents each that asked: "Why haven't we seen a photograph of the whole Earth yet?" During this campaign, Brand met Buckminster Fuller , who offered to help Brand with his project. Several of the pins made their way to NASA employees. The Apollo 17 image, however, released during

452-492: A common barycenter every 27.32 days relative to the background stars. When combined with the Earth–Moon system's common orbit around the Sun, the period of the synodic month , from new moon to new moon, is 29.53 days. Viewed from the celestial north pole , the motion of Earth, the Moon, and their axial rotations are all counterclockwise . Viewed from a vantage point above the Sun and Earth's north poles, Earth orbits in

565-721: A composite image of the Western Hemisphere of Earth titled Blue Marble 2012 . Robert Simmon is most notable for his visualization of the Western Hemisphere. The picture logged over 3.1 million views on the Flickr image hosting website within the first week of release. On February 2, 2012, NASA released a companion to this new Blue Marble , showing a composite image of the Eastern Hemisphere from data obtained on January 23, 2012. The picture

678-548: A counterclockwise direction about the Sun. The orbital and axial planes are not precisely aligned: Earth's axis is tilted some 23.44 degrees from the perpendicular to the Earth–Sun plane (the ecliptic ), and the Earth-Moon plane is tilted up to ±5.1 degrees against the Earth–Sun plane. Without this tilt, there would be an eclipse every two weeks, alternating between lunar eclipses and solar eclipses . The Hill sphere , or

791-566: A cyclone in the Indian Ocean is also visible, the South Asian mainland and Australia is on the eastern limb, and the eastern part of South America lies on the western limb. NASA has also applied the name to a 2012 series of images which cover the entire globe at relatively high resolution. These were created by looking through satellite pictures taken over time in order to find as many cloudless photographs as possible to use in

904-420: A full rotation about its axis so that the Sun returns to the meridian . The orbital speed of Earth averages about 29.78 km/s (107,200 km/h; 66,600 mph), which is fast enough to travel a distance equal to Earth's diameter, about 12,742 km (7,918 mi), in seven minutes, and the distance from Earth to the Moon, 384,400 km (238,900 mi), in about 3.5 hours. The Moon and Earth orbit

1017-421: A globe-spanning mid-ocean ridge system. At Earth's polar regions , the ocean surface is covered by seasonally variable amounts of sea ice that often connects with polar land, permafrost and ice sheets , forming polar ice caps . Earth's land covers 29.2%, or 149 million km (58 million sq mi) of Earth's surface. The land surface includes many islands around the globe, but most of

1130-425: A liquid outer core that generates a magnetosphere capable of deflecting most of the destructive solar winds and cosmic radiation . Earth has a dynamic atmosphere , which sustains Earth's surface conditions and protects it from most meteoroids and UV-light at entry . It has a composition of primarily nitrogen and oxygen . Water vapor is widely present in the atmosphere, forming clouds that cover most of

1243-493: A major issue in filmmaking . Rather than cropping, the cinematographer usually uses mattes to increase the latitude for alternative aspect ratios in projection and broadcast. Anamorphic optics (such as Panavision lenses) produce a full-frame , horizontally compressed image from which broadcasters and projectionists can matte a number of alternative aspect ratios without cropping relevant image detail. Without this, widescreen reproduction, especially for television broadcasting,

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1356-414: A mission. All crew members, Gene Cernan , Ronald Evans and Harrison Schmitt , took photographs during the mission with the onboard Hasselblad. They have largely avoided definitively answering the question of the photographer's identity by each member claiming to have taken it. However, interviews and evidence examined by Eric Hartwell after the mission suggest that Schmitt was the photographer. Apollo 17

1469-435: A printed image, crop marks may be printed at the four corners of the image, just outside the central area to be retained:   ⌏   at the top left corner,   ⌎   at the top right corner,   ⌍   at the bottom left corner, and   ⌌   at the bottom right corner. The paper or paperboard on which the image is printed can then be cut on each side so that the crop marks are removed. In Unicode,

1582-403: A series of shots which were taken just before and are nearly identical, NASA photograph AS17-148-22725 and AS17-148-22726, the second also having been used as a full-Earth image. The widely published versions are cropped and chromatically adjusted from the original photographs. According to the photograph description by NASA it was taken at 05:39 a.m. EST, 5 hours 6 minutes after launch of

1695-484: A similarly manually assembled cloud-cover and night-lights image sets, at lower resolutions. A subsequent release was made in 2005, named Blue Marble Next Generation . This series of digital image mosaics was produced with the aid of automated image-sifting upon images from NASA's Earth Observatory , which enabled the inclusion of a complete, cloud-free globe for each month from January to December 2004, at even higher resolution (500 m/pixel). The original release of

1808-472: A single-image set covering the entire globe could not reflect the extent of seasonal snow-and-vegetative cover across both hemispheres, but this newer release closely modeled the changes of the seasons. A number of interactive viewers for these data have also been released, among them a music visualization for the PlayStation 3 that is based on the texture data. On January 25, 2012, NASA released

1921-411: A surge in environmental activism during the 1970s, became a symbol of the environmental movement , as a depiction of Earth's fragility, vulnerability, and isolation amid the vast expanse of space. Today, as speculated by NASA archivist Mike Gentry, The Blue Marble is among the most widely distributed images in history. The photograph's official NASA designation is AS17-148-22727. It is the third of

2034-449: A technological product produced by a dominant spacefaring country, which developed the image and its overview effect as a boundless worldview instead of as an image inviting an intricate and critical overview . Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life . This is enabled by Earth being an ocean world , the only one in

2147-554: A very wide-angle presentation such as one might get with a fish-eye lens, and it does not include the whole hemisphere. On December 5, 2012, NASA released a nighttime view of Earth called Black Marble during an annual meeting of Earth scientists held by the American Geophysical Union in San Francisco. The images display all the human and natural matter that glows and can be detected from space. The data

2260-514: Is rounded into an ellipsoid with a circumference of about 40,000 km. It is the densest planet in the Solar System . Of the four rocky planets , it is the largest and most massive. Earth is about eight light-minutes away from the Sun and orbits it , taking a year (about 365.25 days) to complete one revolution. Earth rotates around its own axis in slightly less than a day (in about 23 hours and 56 minutes). Earth's axis of rotation

2373-456: Is a chemically distinct silicate solid crust, which is underlain by a highly viscous solid mantle. The crust is separated from the mantle by the Mohorovičić discontinuity . The thickness of the crust varies from about 6 kilometres (3.7 mi) under the oceans to 30–50 km (19–31 mi) for the continents. The crust and the cold, rigid, top of the upper mantle are collectively known as

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2486-483: Is approximately 9.8 m/s (32 ft/s ). Local differences in topography, geology, and deeper tectonic structure cause local and broad regional differences in Earth's gravitational field, known as gravity anomalies . The main part of Earth's magnetic field is generated in the core, the site of a dynamo process that converts the kinetic energy of thermally and compositionally driven convection into electrical and magnetic field energy. The field extends outwards from

2599-638: Is composed of data obtained by the Visible/Infrared Imager Radiometer Suite (VIIRS) instrument on board the Suomi NPP satellite on January 4, 2012. The data was obtained from six orbits of the Earth by the Suomi NPP over an eight-hour period. The image was created using a near-sided perspective projection with the viewing point placed 2,100 km (1,300 miles) above 20° North by 100° West. This projection results in

2712-529: Is contained in 3.45 billion-year-old Australian rocks showing fossils of microorganisms . During the Neoproterozoic , 1000 to 539 Ma , much of Earth might have been covered in ice. This hypothesis has been termed " Snowball Earth ", and it is of particular interest because it preceded the Cambrian explosion , when multicellular life forms significantly increased in complexity. Following

2825-439: Is dependent upon a variety of soft matting techniques such as letterboxing, which involves varying degrees of image cropping (see figures 2, 3 and 4). Since the advent of widescreen television, a similar process has removed large chunks from the top & bottom to make a standard 4:3 image fit a 16:9 one, losing 25 percent of the original image. Another option is a process called pillarboxing , where black bands are placed down

2938-457: Is farthest out from its center of mass at its equatorial bulge, the summit of the volcano Chimborazo in Ecuador (6,384.4 km or 3,967.1 mi) is its farthest point out. Parallel to the rigid land topography the ocean exhibits a more dynamic topography . To measure the local variation of Earth's topography, geodesy employs an idealized Earth producing a geoid shape. Such a shape

3051-479: Is frequently used, as in the Earth flag by environmental activist organizations or companies attempting to promote an environmentally conscious image. There has also been a children's television program called Big Blue Marble . Poet-diplomat Abhay Kumar penned an Earth anthem inspired by the Blue Marble which contains "all the peoples and the nations of the world, one for all, all for one, united we unfurl

3164-516: Is gained if the ocean is idealized, covering Earth completely and without any perturbations such as tides and winds. The result is a smooth but irregular geoid surface, providing a mean sea level (MSL) as a reference level for topographic measurements. Earth's surface is the boundary between the atmosphere, and the solid Earth and oceans. Defined in this way, it has an area of about 510 million km (197 million sq mi). Earth can be divided into two hemispheres : by latitude into

3277-426: Is liquid under normal atmospheric pressure. Differences in the amount of captured energy between geographic regions (as with the equatorial region receiving more sunlight than the polar regions) drive atmospheric and ocean currents , producing a global climate system with different climate regions , and a range of weather phenomena such as precipitation , allowing components such as nitrogen to cycle . Earth

3390-513: Is now slightly longer than it was during the 19th century due to tidal deceleration , each day varies between 0 and 2 ms longer than the mean solar day. Earth's rotation period relative to the fixed stars , called its stellar day by the International Earth Rotation and Reference Systems Service (IERS), is 86,164.0989 seconds of mean solar time ( UT1 ), or 23 56 4.0989 . Earth's rotation period relative to

3503-622: Is rare, though the alternative spelling Gaia has become common due to the Gaia hypothesis , in which case its pronunciation is / ˈ ɡ aɪ . ə / rather than the more classical English / ˈ ɡ eɪ . ə / . There are a number of adjectives for the planet Earth. The word "earthly" is derived from "Earth". From the Latin Terra comes terran / ˈ t ɛr ə n / , terrestrial / t ə ˈ r ɛ s t r i ə l / , and (via French) terrene / t ə ˈ r iː n / , and from

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3616-487: Is that it was formed by accretion from material loosed from Earth after a Mars -sized object with about 10% of Earth's mass, named Theia , collided with Earth. It hit Earth with a glancing blow and some of its mass merged with Earth. Between approximately 4.1 and 3.8 Ga , numerous asteroid impacts during the Late Heavy Bombardment caused significant changes to the greater surface environment of

3729-453: Is the basis for the astronomical unit (AU) and is equal to roughly 8.3 light minutes or 380 times Earth's distance to the Moon . Earth orbits the Sun every 365.2564 mean solar days , or one sidereal year . With an apparent movement of the Sun in Earth's sky at a rate of about 1°/day eastward, which is one apparent Sun or Moon diameter every 12 hours. Due to this motion, on average it takes 24 hours—a solar day—for Earth to complete

3842-572: Is the second time such a photo was taken by a person after the 1968 photograph Earthrise taken by William Anders of Apollo 8 . Before the Blue Marble a picture of the fully illuminated Earth by the ATS-3 satellite was used in 1968 by Stewart Brand for his Whole Earth Catalog , after campaigning since 1966 to have NASA release a then-rumored satellite image of the entire Earth as seen from space. He got inspired during an LSD trip, seeing

3955-457: Is tied to that of the Sun. Over the next 1.1 billion years , solar luminosity will increase by 10%, and over the next 3.5 billion years by 40%. Earth's increasing surface temperature will accelerate the inorganic carbon cycle , possibly reducing CO 2 concentration to levels lethally low for current plants ( 10  ppm for C4 photosynthesis ) in approximately 100–900 million years . A lack of vegetation would result in

4068-405: Is tilted with respect to the perpendicular to its orbital plane around the Sun, producing seasons . Earth is orbited by one permanent natural satellite , the Moon , which orbits Earth at 384,400 km (1.28 light seconds) and is roughly a quarter as wide as Earth. The Moon's gravity helps stabilize Earth's axis, causes tides and gradually slows Earth's rotation . Tidal locking has made

4181-583: The Milky Way and orbits about 28,000  light-years from its center. It is about 20 light-years above the galactic plane in the Orion Arm . The axial tilt of Earth is approximately 23.439281° with the axis of its orbit plane, always pointing towards the Celestial Poles . Due to Earth's axial tilt, the amount of sunlight reaching any given point on the surface varies over the course of

4294-759: The Pacific , North American , Eurasian , African , Antarctic , Indo-Australian , and South American . Other notable plates include the Arabian Plate , the Caribbean Plate , the Nazca Plate off the west coast of South America and the Scotia Plate in the southern Atlantic Ocean. The Australian Plate fused with the Indian Plate between 50 and 55 Ma . The fastest-moving plates are

4407-732: The Solar System sustaining liquid surface water . Almost all of Earth's water is contained in its global ocean, covering 70.8% of Earth's crust . The remaining 29.2% of Earth's crust is land, most of which is located in the form of continental landmasses within Earth's land hemisphere . Most of Earth's land is at least somewhat humid and covered by vegetation , while large sheets of ice at Earth's polar deserts retain more water than Earth's groundwater , lakes, rivers and atmospheric water combined. Earth's crust consists of slowly moving tectonic plates , which interact to produce mountain ranges, volcanoes , and earthquakes. Earth has

4520-805: The South Pole facing upwards, The Blue Marble shows Earth from the Mediterranean Sea to Antarctica . This was the first time the Apollo trajectory made it possible to photograph the south polar ice cap , despite the Southern Hemisphere being heavily covered in clouds . In addition to the Arabian Peninsula and Madagascar , almost the entire coastline of Africa and most of the Indian Ocean are clearly visible,

4633-419: The asthenosphere , the solid but less-viscous part of the upper mantle that can flow and move along with the plates. As the tectonic plates migrate, oceanic crust is subducted under the leading edges of the plates at convergent boundaries. At the same time, the upwelling of mantle material at divergent boundaries creates mid-ocean ridges. The combination of these processes recycles the oceanic crust back into

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4746-415: The celestial equator , this is equivalent to an apparent diameter of the Sun or the Moon every two minutes; from Earth's surface, the apparent sizes of the Sun and the Moon are approximately the same. Earth orbits the Sun, making Earth the third-closest planet to the Sun and part of the inner Solar System . Earth's average orbital distance is about 150 million km (93 million mi), which

4859-408: The ocean floor form the top of Earth's crust , which together with parts of the upper mantle form Earth's lithosphere . Earth's crust may be divided into oceanic and continental crust. Beneath the ocean-floor sediments, the oceanic crust is predominantly basaltic , while the continental crust may include lower density materials such as granite , sediments and metamorphic rocks. Nearly 75% of

4972-430: The precessing or moving mean March equinox (when the Sun is at 90° on the equator), is 86,164.0905 seconds of mean solar time (UT1) (23 56 4.0905 ) . Thus the sidereal day is shorter than the stellar day by about 8.4 ms. Apart from meteors within the atmosphere and low-orbiting satellites, the main apparent motion of celestial bodies in Earth's sky is to the west at a rate of 15°/h = 15'/min. For bodies near

5085-413: The sphere of gravitational influence , of Earth is about 1.5 million km (930,000 mi) in radius. This is the maximum distance at which Earth's gravitational influence is stronger than that of the more distant Sun and planets. Objects must orbit Earth within this radius, or they can become unbound by the gravitational perturbation of the Sun. Earth, along with the Solar System, is situated in

5198-464: The "last ice age", covered large parts of the continents, to the middle latitudes, in ice and ended about 11,700 years ago. Chemical reactions led to the first self-replicating molecules about four billion years ago. A half billion years later, the last common ancestor of all current life arose. The evolution of photosynthesis allowed the Sun's energy to be harvested directly by life forms. The resultant molecular oxygen ( O 2 ) accumulated in

5311-425: The Apollo 17 mission, and about 1 hour 54 minutes after the spacecraft left its parking orbit around Earth to begin its trajectory to the Moon . Alternatively, Eric Hartwell has identified it as having been taken slightly earlier at 5 hours 3 minutes, when one crew member states having changed the f-number , presumably between AS17-148-22725, the first of the series of photos, and the following less exposed images like

5424-591: The Atlantic and Pacific Oceans, major slowly moving "cloud rivers", dust aerosol plumes from Africa, the Sun's reflection in the oceans, ship exhaust tracks in the clouds, rivers and lakes, and the variegated land surface patterns especially in the African deserts. The spatial resolution of the color images is about 10 km (6 miles), and the resolution of the science products will be about 20 km (10 miles). Once every three months, lunar images are obtained that are

5537-460: The Blue Marble. At that time, Africa was in noon daylight and with the December solstice approaching, Antarctica was also illuminated. The photograph is at times oriented with Earth's south pointing up , relative to the capsule. The picture shows many weather systems, featuring a Shapyro–Keyser cyclone near to the center of the image. Cyclone Sixteen (16B) can be seen in the upper right of

5650-484: The Cambrian explosion, 535 Ma , there have been at least five major mass extinctions and many minor ones. Apart from the proposed current Holocene extinction event, the most recent was 66 Ma , when an asteroid impact triggered the extinction of non-avian dinosaurs and other large reptiles, but largely spared small animals such as insects, mammals , lizards and birds. Mammalian life has diversified over

5763-402: The Earth's South Pole facing upwards and the Sun above them (in spatial navigation terms, to their zenith ) when they took the image. To the astronauts , the Earth had the appearance and size of a glass marble . The Blue Marble was not the first clear color image taken of an illuminated face of Earth , since such images by satellites had already been made and released as early as 1967, and

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5876-654: The Earth. Terra is also the name of the planet in some Romance languages , languages that evolved from Latin , like Italian and Portuguese , while in other Romance languages the word gave rise to names with slightly altered spellings, like the Spanish Tierra and the French Terre . The Latinate form Gæa or Gaea ( English: / ˈ dʒ iː . ə / ) of the Greek poetic name Gaia ( Γαῖα ; Ancient Greek : [ɡâi̯.a] or [ɡâj.ja] )

5989-533: The Latin Tellus comes tellurian / t ɛ ˈ l ʊər i ə n / and telluric . The oldest material found in the Solar System is dated to 4.5682 +0.0002 −0.0004 Ga (billion years) ago. By 4.54 ± 0.04 Ga the primordial Earth had formed. The bodies in the Solar System formed and evolved with the Sun. In theory, a solar nebula partitions a volume out of a molecular cloud by gravitational collapse, which begins to spin and flatten into

6102-758: The Moon always face Earth with the same side. Earth, like most other bodies in the Solar System, formed 4.5 billion years ago from gas and dust in the early Solar System . During the first billion years of Earth's history , the ocean formed and then life developed within it. Life spread globally and has been altering Earth's atmosphere and surface, leading to the Great Oxidation Event two billion years ago. Humans emerged 300,000 years ago in Africa and have spread across every continent on Earth. Humans depend on Earth's biosphere and natural resources for their survival, but have increasingly impacted

6215-426: The Moon and, by inference, to that of Earth. Earth's atmosphere and oceans were formed by volcanic activity and outgassing . Water vapor from these sources condensed into the oceans, augmented by water and ice from asteroids, protoplanets , and comets . Sufficient water to fill the oceans may have been on Earth since it formed. In this model, atmospheric greenhouse gases kept the oceans from freezing when

6328-458: The Solar System's planetary-sized objects, Earth is the object with the highest density . Earth's mass is approximately 5.97 × 10   kg ( 5.970  Yg ). It is composed mostly of iron (32.1% by mass ), 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 gravitational separation ,

6441-403: The Sun when the star reaches its maximum radius, otherwise, with tidal effects, it may enter the Sun's atmosphere and be vaporized. Earth has a rounded shape , through hydrostatic equilibrium , with an average diameter of 12,742 kilometres (7,918 mi), making it the fifth largest planetary sized and largest terrestrial object of the Solar System . Due to Earth's rotation it has

6554-425: The atmosphere and due to interaction with ultraviolet solar radiation, formed a protective ozone layer ( O 3 ) in the upper atmosphere. The incorporation of smaller cells within larger ones resulted in the development of complex cells called eukaryotes . True multicellular organisms formed as cells within colonies became increasingly specialized. Aided by the absorption of harmful ultraviolet radiation by

6667-476: The average human eye. In addition to images, scientific information will be uploaded as it becomes available after in-flight calibration is complete. The science information will be ozone and aerosol amounts, cloud reflectivity, cloud height, and vegetation information. The EPIC instrument views the Earth from sunrise in the west to sunset in the east 12 to 13 times per day as the Earth rotates at 15 degrees of longitude per hour. Clearly visible are storms forming over

6780-487: The blue marble flag". In 2002, NASA released an extensive set of satellite-captured imagery, including prepared images suitable for direct human viewing, as well as complete sets suitable for use in preparing further works. At the time, 1 km/pixel was the most detailed imagery available for free, and permitted for reuse without a need for extensive preparatory work to eliminate cloud cover and conceal missing data, or to parse specialized data formats. The data also included

6893-492: The case of the Black Marble images to emphasize the city lights. The images have been used to study the spatial distribution of economic activity, to select sites for astronomical observatories, and to monitor human activities around protected areas. On July 21, 2015, NASA released a new Blue Marble photograph taken by a U.S. Deep Space Climate Observatory (DSCOVR), a solar weather and Earth observation satellite that

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7006-450: The center, the temperature may be up to 6,000 °C (10,830 °F), and the pressure could reach 360  GPa (52 million  psi ). Because much of the heat is provided by radioactive decay, scientists postulate that early in Earth's history, before isotopes with short half-lives were depleted, Earth's heat production was much higher. At approximately 3  Gyr , twice the present-day heat would have been produced, increasing

7119-454: The continental crust , particularly during the early stages of Earth's history. New continental crust forms as a result of plate tectonics , a process ultimately driven by the continuous loss of heat from Earth's interior. Over the period of hundreds of millions of years, tectonic forces have caused areas of continental crust to group together to form supercontinents that have subsequently broken apart. At approximately 750 Ma , one of

7232-616: The continental surfaces are covered by sedimentary rocks, although they form about 5% of the mass of the crust. Earth's surface topography comprises both the topography of the ocean surface , and the shape of Earth's land surface. The submarine terrain of the ocean floor has an average bathymetric depth of 4 km, and is as varied as the terrain above sea level. Earth's surface is continually being shaped by internal plate tectonic processes including earthquakes and volcanism ; by weathering and erosion driven by ice, water, wind and temperature; and by biological processes including

7345-419: The core are chaotic; the magnetic poles drift and periodically change alignment. This causes secular variation of the main field and field reversals at irregular intervals averaging a few times every million years. The most recent reversal occurred approximately 700,000 years ago. The extent of Earth's magnetic field in space defines the magnetosphere . Ions and electrons of the solar wind are deflected by

7458-527: The core is primarily composed of the denser elements: iron (88.8%), with smaller amounts of nickel (5.8%), sulfur (4.5%), and less than 1% trace elements. The most common rock constituents of the crust are oxides . Over 99% of the crust is composed of various oxides of eleven elements, principally oxides containing silicon (the silicate minerals ), aluminium, iron, calcium, magnesium, potassium, or sodium. The major heat-producing isotopes within Earth are potassium-40 , uranium-238 , and thorium-232 . At

7571-463: The core, through the mantle, and up to Earth's surface, where it is, approximately, a dipole . The poles of the dipole are located close to Earth's geographic poles. At the equator of the magnetic field, the magnetic-field strength at the surface is 3.05 × 10 T , with a magnetic dipole moment of 7.79 × 10 Am at epoch 2000, decreasing nearly 6% per century (although it still remains stronger than its long time average). The convection movements in

7684-431: The crop marks are represented by: Crop marks are useful for cropping images printed with bleed , and more generally, when the position of an image on the final sheet is not precisely known in advance. In certain circumstances, film footage may be cropped to change it from one aspect ratio to another, without stretching the image or filling the blank spaces with letterbox bars (fig. 2). Concerns about aspect ratios are

7797-539: The days shorter. Above the Arctic Circle and below the Antarctic Circle there is no daylight at all for part of the year, causing a polar night , and this night extends for several months at the poles themselves. These same latitudes also experience a midnight sun , where the sun remains visible all day. By astronomical convention, the four seasons can be determined by the solstices—the points in

7910-611: The earliest known supercontinents, Rodinia , began to break apart. The continents later recombined to form Pannotia at 600–540 Ma , then finally Pangaea , which also began to break apart at 180 Ma . The most recent pattern of ice ages began about 40 Ma , and then intensified during the Pleistocene about 3 Ma . High- and middle-latitude regions have since undergone repeated cycles of glaciation and thaw, repeating about every 21,000, 41,000 and 100,000 years. The Last Glacial Period , colloquially called

8023-544: The equally large area of land under permafrost ) or deserts (33%). The pedosphere is the outermost layer of Earth's land surface and is composed of soil and subject to soil formation processes. Soil is crucial for land to be arable. Earth's total arable land is 10.7% of the land surface, with 1.3% being permanent cropland. Earth has an estimated 16.7 million km (6.4 million sq mi) of cropland and 33.5 million km (12.9 million sq mi) of pastureland. The land surface and

8136-473: The final images. NASA has verified that the 2012 "blue marble" images are composites, made from multiple images taken in low Earth orbit. Likewise, these images do not fit together properly and due to lighting, weather and cloud interference it is impossible to collect cohesive or fully clear images of the entire Earth simultaneously. The photograph, taken on December 7, 1972, is one of the most widely distributed photographic images in existence. The astronauts had

8249-638: The growth and decomposition of biomass into soil . Earth's mechanically rigid outer layer of Earth's crust and upper mantle , the lithosphere , is divided into tectonic plates . These plates are rigid segments that move relative to each other at one of three boundaries types: at convergent boundaries , two plates come together; at divergent boundaries , two plates are pulled apart; and at transform boundaries , two plates slide past one another laterally. Along these plate boundaries, earthquakes, volcanic activity , mountain-building , and oceanic trench formation can occur. The tectonic plates ride on top of

8362-404: The heat in Earth is lost through plate tectonics, by mantle upwelling associated with mid-ocean ridges . The final major mode of heat loss is through conduction through the lithosphere, the majority of which occurs under the oceans. The gravity of Earth is the acceleration that is imparted to objects due to the distribution of mass within Earth. Near Earth's surface, gravitational acceleration

8475-466: The image. This storm had brought flooding and high winds to the Indian state of Tamil Nadu on December 5, two days before the photograph was taken. This image has also been used to validate state-of-the-art atmospheric reanalysis fifty years after it was taken. The photographer used a 70-millimeter Hasselblad camera with an 80-millimeter Zeiss lens. NASA generally credits images to the whole crew of

8588-406: The land surface is taken by the four continental landmasses , which are (in descending order): Africa-Eurasia , America (landmass) , Antarctica , and Australia (landmass) . These landmasses are further broken down and grouped into the continents . The terrain of the land surface varies greatly and consists of mountains, deserts , plains , plateaus , and other landforms . The elevation of

8701-513: The land surface varies from a low point of −418 m (−1,371 ft) at the Dead Sea , to a maximum altitude of 8,848 m (29,029 ft) at the top of Mount Everest . The mean height of land above sea level is about 797 m (2,615 ft). Land can be covered by surface water , snow, ice, artificial structures or vegetation. Most of Earth's land hosts vegetation, but considerable amounts of land are ice sheets (10%, not including

8814-399: The lithosphere, which is divided into independently moving tectonic plates. Beneath the lithosphere is the asthenosphere , a relatively low-viscosity layer on which the lithosphere rides. Important changes in crystal structure within the mantle occur at 410 and 660 km (250 and 410 mi) below the surface, spanning a transition zone that separates the upper and lower mantle. Beneath

8927-410: The loss of oxygen in the atmosphere, making current animal life impossible. Due to the increased luminosity, Earth's mean temperature may reach 100 °C (212 °F) in 1.5 billion years, and all ocean water will evaporate and be lost to space, which may trigger a runaway greenhouse effect , within an estimated 1.6 to 3 billion years. Even if the Sun were stable, a fraction of the water in

9040-456: The lowercase when it is preceded by "the", such as "the atmosphere of the earth". It almost always appears in lowercase in colloquial expressions such as "what on earth are you doing?" The name Terra / ˈ t ɛr ə / occasionally is used in scientific writing and especially in science fiction to distinguish humanity's inhabited planet from others, while in poetry Tellus / ˈ t ɛ l ə s / has been used to denote personification of

9153-497: The magnetosphere. During magnetic storms and substorms , charged particles can be deflected from the outer magnetosphere and especially the magnetotail, directed along field lines into Earth's ionosphere , where atmospheric atoms can be excited and ionized, causing an aurora . Earth's rotation period relative to the Sun—its mean solar day—is 86,400 seconds of mean solar time ( 86,400.0025 SI seconds ). Because Earth's solar day

9266-409: The magnetosphere; solar wind pressure compresses the day-side of the magnetosphere, to about 10 Earth radii, and extends the night-side magnetosphere into a long tail. Because the velocity of the solar wind is greater than the speed at which waves propagate through the solar wind, a supersonic bow shock precedes the day-side magnetosphere within the solar wind. Charged particles are contained within

9379-483: The magnetosphere; the plasmasphere is defined by low-energy particles that essentially follow magnetic field lines as Earth rotates. The ring current is defined by medium-energy particles that drift relative to the geomagnetic field, but with paths that are still dominated by the magnetic field, and the Van Allen radiation belts are formed by high-energy particles whose motion is essentially random, but contained in

9492-417: The mantle, an extremely low viscosity liquid outer core lies above a solid inner core . Earth's inner core may be rotating at a slightly higher angular velocity than the remainder of the planet, advancing by 0.1–0.5° per year, although both somewhat higher and much lower rates have also been proposed. The radius of the inner core is about one-fifth of that of Earth. The density increases with depth. Among

9605-612: The mantle. Due to this recycling, most of the ocean floor is less than 100 Ma old. The oldest oceanic crust is located in the Western Pacific and is estimated to be 200 Ma old. By comparison, the oldest dated continental crust is 4,030 Ma , although zircons have been found preserved as clasts within Eoarchean sedimentary rocks that give ages up to 4,400 Ma , indicating that at least some continental crust existed at that time. The seven major plates are

9718-548: The modern oceans will descend to the mantle , due to reduced steam venting from mid-ocean ridges. The Sun will evolve to become a red giant in about 5 billion years . Models predict that the Sun will expand to roughly 1  AU (150 million km; 93 million mi), about 250 times its present radius. Earth's fate is less clear. As a red giant, the Sun will lose roughly 30% of its mass, so, without tidal effects, Earth will move to an orbit 1.7 AU (250 million km; 160 million mi) from

9831-399: The mother of Thor . Historically, "Earth" has been written in lowercase. Beginning with the use of Early Middle English , its definite sense as "the globe" was expressed as "the earth". By the era of Early Modern English , capitalization of nouns began to prevail , and the earth was also written the Earth , particularly when referenced along with other heavenly bodies. More recently,

9944-424: The name is sometimes simply given as Earth , by analogy with the names of the other planets , though "earth" and forms with "the earth" remain common. House styles now vary: Oxford spelling recognizes the lowercase form as the more common, with the capitalized form an acceptable variant. Another convention capitalizes "Earth" when appearing as a name, such as a description of the "Earth's atmosphere", but employs

10057-425: The newly forming Sun had only 70% of its current luminosity . By 3.5 Ga , Earth's magnetic field was established, which helped prevent the atmosphere from being stripped away by the solar wind . As the molten outer layer of Earth cooled it formed the first solid crust , which is thought to have been mafic in composition. The first continental crust , which was more felsic in composition, formed by

10170-593: The ocean may have covered Earth completely. The world ocean is commonly divided into the Pacific Ocean, Atlantic Ocean, Indian Ocean, Antarctic or Southern Ocean , and Arctic Ocean, from largest to smallest. The ocean covers Earth's oceanic crust , with the shelf seas covering the shelves of the continental crust to a lesser extent. The oceanic crust forms large oceanic basins with features like abyssal plains , seamounts , submarine volcanoes , oceanic trenches , submarine canyons , oceanic plateaus , and

10283-670: The oceanic plates, with the Cocos Plate advancing at a rate of 75 mm/a (3.0 in/year) and the Pacific Plate moving 52–69 mm/a (2.0–2.7 in/year). At the other extreme, the slowest-moving plate is the South American Plate, progressing at a typical rate of 10.6 mm/a (0.42 in/year). Earth's interior, like that of the other terrestrial planets, is divided into layers by their chemical or physical ( rheological ) properties. The outer layer

10396-599: The orbit of maximum axial tilt toward or away from the Sun—and the equinoxes , when Earth's rotational axis is aligned with its orbital axis. In the Northern Hemisphere, winter solstice currently occurs around 21 December; summer solstice is near 21 June, spring equinox is around 20 March and autumnal equinox is about 22 or 23 September. In the Southern Hemisphere, the situation is reversed, with

10509-414: The original. However, using texture synthesis , it is possible to artificially add a band around an image, synthetically "uncropping" it. This is effective if the band smoothly blends with the existing image, which is relatively easy if the edge of the image has low detail or is a chaotic natural pattern such as sky or grass, but does not work if discernible objects are cut off at the boundary, such as half

10622-649: The ozone layer, life colonized Earth's surface. Among the earliest fossil evidence for life is microbial mat fossils found in 3.48 billion-year-old sandstone in Western Australia , biogenic graphite found in 3.7 billion-year-old metasedimentary rocks in Western Greenland , and remains of biotic material found in 4.1 billion-year-old rocks in Western Australia. The earliest direct evidence of life on Earth

10735-474: The partial melting of this mafic crust. The presence of grains of the mineral zircon of Hadean age in Eoarchean sedimentary rocks suggests that at least some felsic crust existed as early as 4.4 Ga , only 140  Ma after Earth's formation. There are two main models of how this initial small volume of continental crust evolved to reach its current abundance: (1) a relatively steady growth up to

10848-501: The past 66 Mys , and several million years ago, an African ape species gained the ability to stand upright. This facilitated tool use and encouraged communication that provided the nutrition and stimulation needed for a larger brain, which led to the evolution of humans . The development of agriculture , and then civilization , led to humans having an influence on Earth and the nature and quantity of other life forms that continues to this day. Earth's expected long-term future

10961-549: The periphery of a photograph , change its aspect ratio, or improve the overall composition . In telephoto photography, most commonly in avian and aviation photography , an image is cropped to magnify the primary subject and further reduce the angle of view . When a lens of sufficient focal length to achieve the desired magnification directly is not available. It is considered one of the few editing actions permissible in modern photojournalism along with tonal balance, color correction and sharpening . A cropping made by trimming off

11074-478: The planet's environment . Humanity's current impact on Earth's climate and biosphere is unsustainable , threatening the livelihood of humans and many other forms of life, and causing widespread extinctions . The Modern English word Earth developed, via Middle English , from an Old English noun most often spelled eorðe . It has cognates in every Germanic language , and their ancestral root has been reconstructed as * erþō . In its earliest attestation,

11187-400: The planet. The water vapor acts as a greenhouse gas and, together with other greenhouse gases in the atmosphere, particularly carbon dioxide (CO 2 ), creates the conditions for both liquid surface water and water vapor to persist via the capturing of energy from the Sun's light . This process maintains the current average surface temperature of 14.76 °C (58.57 °F), at which water

11300-421: The polar Northern and Southern hemispheres; or by longitude into the continental Eastern and Western hemispheres. Most of Earth's surface is ocean water: 70.8% or 361 million km (139 million sq mi). This vast pool of salty water is often called the world ocean , and makes Earth with its dynamic hydrosphere a water world or ocean world . Indeed, in Earth's early history

11413-495: The present day, which is supported by the radiometric dating of continental crust globally and (2) an initial rapid growth in the volume of continental crust during the Archean , forming the bulk of the continental crust that now exists, which is supported by isotopic evidence from hafnium in zircons and neodymium in sedimentary rocks. The two models and the data that support them can be reconciled by large-scale recycling of

11526-493: The rates of mantle convection and plate tectonics, and allowing the production of uncommon igneous rocks such as komatiites that are rarely formed today. The mean heat loss from Earth is 87 mW m , for a global heat loss of 4.42 × 10  W . A portion of the core's thermal energy is transported toward the crust by mantle plumes , a form of convection consisting of upwellings of higher-temperature rock. These plumes can produce hotspots and flood basalts . More of

11639-490: The same as those viewed from Earth during a full Moon. On occasion, the other side of the Moon will appear in the Earth images as the Moon crosses in front of the Earth. The picture has been identified as one of the most widely publicised and influential images since its release, particularly in the advocacy for environmental protection. The Blue Marble , and other images from space, have been in parts critically analyzed as distracting from human geographic issues and from being

11752-522: The shape of an ellipsoid , bulging at its Equator ; its diameter is 43 kilometres (27 mi) longer there than at its poles . Earth's shape also has local topographic variations; the largest local variations, like the Mariana Trench (10,925 metres or 35,843 feet below local sea level), shortens Earth's average radius by 0.17% and Mount Everest (8,848 metres or 29,029 feet above local sea level) lengthens it by 0.14%. Since Earth's surface

11865-412: The sides of the screen, allowing the original image to be shown full-frame within the wider aspect ratio (fig. 6). Various methods may be used following cropping or may be used on the original image. It is not possible to "uncrop" a cropped digital image unless the original still exists or undo information exists: if an image is cropped and saved (without undo information), it cannot be recovered without

11978-426: The summer and winter solstices exchanged and the spring and autumnal equinox dates swapped. Cropping (image) In the printing, graphic design and photography industries, cropping is the removal of unwanted areas from the periphery of a photographic or illustrated image . Cropping is one of the most basic photo manipulation processes, and it is carried out to remove an unwanted object or irrelevant noise from

12091-530: The surface in a polar orbit. The nighttime views were obtained with the new satellite's "day-night band" of the Visible Infrared Imaging Radiometer Suite (VIIRS), which detects light in a range of wavelengths from green to near-infrared, and uses filtering techniques to observe dim signals such as city lights, gas flares, auroras, wildfires, and reflected moonlight. Auroras, fires, and other stray light have been removed in

12204-471: The top and bottom margins of a photograph, or a film, produces a view that mimics the panoramic format (in photography) or the widescreen format in cinematography and broadcasting . Neither of these formats is cropped as such, but rather they are products of highly specialized optical configurations and camera designs. Cropping in order to emphasize the subject: Cropping in order to remove unwanted details/objects: To assist in precise cropping of

12317-461: The word eorðe was used to translate the many senses of Latin terra and Greek γῆ gē : the ground, its soil , dry land, the human world, the surface of the world (including the sea), and the globe itself. As with Roman Terra /Tellūs and Greek Gaia , Earth may have been a personified goddess in Germanic paganism : late Norse mythology included Jörð ("Earth"), a giantess often given as

12430-550: The year. This causes the seasonal change in climate, with summer in the Northern Hemisphere occurring when the Tropic of Cancer is facing the Sun, and in the Southern Hemisphere when the Tropic of Capricorn faces the Sun. In each instance, winter occurs simultaneously in the opposite hemisphere. During the summer, the day lasts longer, and the Sun climbs higher in the sky. In winter, the climate becomes cooler and

12543-541: Was acquired by the Suomi NPP satellite in April and October 2012 and then mapped over existing Blue Marble imagery of Earth to provide a realistic view of the planet. The Suomi NPP satellite completed 312 orbits and gathered 2.5 terabytes of data to get a clear shot of every parcel of the Earth's land surface. Named for satellite meteorology pioneer Verner Suomi , the satellite flies over any given point on Earth's surface twice each day and flies 512 miles (824 km) above

12656-685: Was launched in February 2015 and provided a near-continuous view of the entire sunlit-side of the Earth. The image was taken on July 6, 2015. The photograph, of the Western Hemisphere , is centered over Central America. The Western United States, Mexico and the Caribbean are visible, but much of South America is hidden beneath cloud cover. Greenland can be seen at the upper edge of the image. The EPIC science team plans to upload 13 new color images per day on their website. The color balance has been adjusted to approximate an image that could be seen with

12769-409: Was the last crewed lunar mission. No human since has been far enough from Earth to photograph a whole-Earth image such as The Blue Marble , but whole-Earth images have been taken by many uncrewed spacecraft missions. Subsequent similar images of Earth (including composites at much higher resolution) have also been termed Blue Marble images, and the phrase "blue marble" (as well as the picture itself)

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