Misplaced Pages

#395604

127-511: The winter solstice , also called the hibernal solstice , occurs when either of Earth 's poles reaches its maximum tilt away from the Sun . This happens twice yearly, once in each hemisphere ( Northern and Southern ). For that hemisphere, the winter solstice is the day with the shortest period of daylight and longest night of the year, and when the Sun is at its lowest daily maximum elevation in

254-491: 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

381-470: A certain point around that time. The earliest sunset and latest sunrise dates differ from winter solstice, however, and these depend on latitude, due to the variation in the solar day throughout the year caused by the Earth's elliptical orbit (see earliest and latest sunrise and sunset ). Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life . This

508-492: 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

635-548: 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

762-420: 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

889-421: 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

1016-523: A gold medallion from his reign depict the Emperor's bust in profile twinned ( jugate ) with Sol Invictus, with the legend INVICTUS CONSTANTINUS Constantine decreed (March 7, 321) DIES SOLIS  – the day of the Sun, " Sunday " – as the Roman day of rest On the venerable day of the Sun let the magistrates and people residing in cities rest, and let all workshops be closed. In

1143-425: 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

1270-530: A professor at Trinity College Dublin , though this theory "is nowadays used as the default explanation for the choice of 25 December as Christ's birthday, few advocates of this theory seem to be aware of how paltry the available evidence actually is." In Anglo-Saxon England the winter solstice was generally deemed to be December 25, and in Old English , midwinter could mean both the winter solstice and Christmas . The North Germanic peoples celebrated

1397-648: A restoration of a portico of Sol in what is now the Trastevere area of Rome by a certain Gaius Iulius Anicetus. While he may have had in mind an allusion to his own cognomen , which is the Latinized form of the Greek equivalent of invictus , ἀνίκητος ( anikētos ), the earliest extant dated inscription that uses invictus as an epithet of Sol is from CE 158. Another, stylistically dated to

SECTION 10

#1732766162396

1524-526: A wide range of legends, only a few of which incorporated the epithet INVICTUS , such as the legend SOLI INVICTO COMITI , claiming the "Unconquered Sun" as a companion to the Emperor, used with particular frequency by Constantine. Statuettes of Sol Invictus, carried by the standard-bearers, appear in three places in reliefs on the Arch of Constantine . Constantine's official coinage continues to bear images of Sol until 325/326. A solidus of Constantine as well as

1651-730: A winter holiday called Yule . The Heimskringla , written in the 13th century by the Icelander Snorri Sturluson , describes a Yule feast hosted by the Norwegian king Haakon the Good (c. 920–961). According to Snorri, the Christian Haakon had moved Yule from "midwinter" and aligned it with the Christian Christmas celebration. Historically, this has made some scholars believe that Yule originally

1778-514: 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

1905-456: 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

2032-602: Is a festival day in the Hindu calendar , in reference to deity Surya (sun). It is observed each year in January. It marks the first day of Sun's transit into Makara (Capricorn) , marking the end of the month with the winter solstice and the start of longer days. Iranian people celebrate the night of the Northern Hemisphere's winter solstice as, " Yalda night ", which is known to be the "longest and darkest night of

2159-483: 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

2286-658: Is broad agreement that coin-images showing the imperial radiate crown are stylistically distinct from those of the solar crown of rays; the imperial radiate crown is depicted as a real object rather than as symbolic light. Hijmans argues that the Imperial radiate crown represents the honorary wreath awarded to Augustus , perhaps posthumously, to commemorate his victory at the Battle of Actium ; he points out that henceforth, living emperors were depicted with radiate crowns, but state divi were not. Hijmans believes this implies that

2413-473: Is celebrated between December 22 and January 6. Buzmi is a ritualistic piece of wood (or several pieces of wood) that is put to burn in the fire ( zjarri ) of the hearth ( vatër ) on the night of a winter celebration that falls after the return of the Sun for summer (after the winter solstice), sometimes on the night of Kërshëndella on December 24 ( Christmas Eve ), sometimes on the night of kolendra , or sometimes on New Year's Day or on any other occasion aound

2540-529: 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

2667-792: Is enabled by Earth being an ocean world , the only one in 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

SECTION 20

#1732766162396

2794-457: 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

2921-516: 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

3048-426: 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

3175-579: Is mentioned in an annotation of uncertain date added to a manuscript by 12th-century Syrian bishop Jacob Bar-Salibi . The scribe wrote: It was a custom of the Pagans to celebrate on the same 25 December the birthday of the Sun, at which they kindled lights in token of festivity. In these solemnities and revelries, the Christians also took part. Accordingly, when the doctors of the Church perceived that

3302-513: 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

3429-622: 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

3556-487: 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

3683-453: 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

3810-457: 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

3937-455: 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

Winter solstice - Misplaced Pages Continue

4064-475: The Saturnalia (December 17–23), Rome's most joyous holiday season since Republican times, characterized by parties, banquets, and exchanges of gifts". A widely-held theory is that the Church chose December 25 as Christ's birthday ( Dies Natalis Christi ) to appropriate the Roman winter solstice festival marking the sun god's birthday ( Dies Natalis Solis Invicti ). According to C. Philipp E. Nothaft,

4191-583: 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

4318-759: 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

4445-419: 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

4572-415: 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

4699-408: 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

4826-430: 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

4953-413: 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

5080-632: The talmudic hypothesis that Adam first established the tradition of fasting before the winter solstice , and rejoicing afterward, which festival later developed into the Roman Saturnalia and Kalendae . When the First Man saw that the day was continuously shortening, he said, "Woe is me! Because I have sinned, the world darkens around me, and returns to formlessless and void. This is the death to which Heaven has sentenced me!" He decided to spend eight days in fasting and prayer. When he saw

5207-447: The "extreme of winter" ( Dongzhi ), or the "shortest day". Since prehistory, the winter solstice has been a significant time of year in many cultures and has been marked by festivals and rites . It marked the symbolic death and rebirth of the Sun; the gradual waning of daylight hours is reversed and begins to grow again. Some ancient monuments such as Newgrange , Stonehenge , Cahokia Woodhenge , and Ahu Tongariki are aligned with

Winter solstice - Misplaced Pages Continue

5334-464: 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

5461-598: The 2nd century, is inscribed on a Roman phalera (ornamental disk): INVENTORI LUCIS SOLI INVICTO AUGUSTO ( "I glorify the unconquerable sun, the creator of light." ) Augustus is a regular epithet linking deities to the Imperial cult . Sol Invictus played a prominent role in the Mithraic mysteries , and was equated with Mithras. The relation of the Mithraic Sol Invictus to the public cult of

5588-404: The 3rd century BCE. The Roman cult to Sol is continuous from the "earliest history" of the city until the institution of Christianity as the exclusive state religion. Scholars have sometimes regarded the traditional Sol Indiges and Sol Invictus as two separate deities, but the rejection of this view by S. E. Hijmans has found supporters. An inscription of CE 102 records

5715-484: 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

5842-471: The Christians had a leaning to this festival, they took counsel and resolved that the true Nativity should be solemnised on that day. Another theory is that Christmas was calculated as nine months after a date chosen as Christ's conception (the Annunciation ): March 25, the Roman date of the spring equinox . This theory was first proposed by French writer Louis Duchesne in 1889. The charioteer in

5969-602: 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] )

6096-571: The East, the Emperor Aurelian thoroughly reformed the Roman cult of Sol, elevating the sun-god to one of the premier divinities of the Empire. Where previously priests of Sol had been simply sacerdotes and tended to belong to lower ranks of Roman society, they were now pontifices and members of the new college of pontifices instituted by Aurelian. Every pontifex of Sol was a member of

6223-533: 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

6350-758: 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

6477-426: 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

SECTION 50

#1732766162396

6604-578: The Roman Saturnalia and Calenda. A mosaic floor in Hamat Tiberias presents David as Helios surrounded by a ring with the signs of the zodiac . As well as in Hamat Tiberias, figures of Helios or Sol Invictus also appear in several of the very few surviving schemes of decoration surviving from Late Antique synagogues , including Beth Alpha , Husefa, all now in Israel , and Naaran in

6731-458: 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 ,

6858-531: The Sun has also been used in early Jewish prophecy, poetry, and art. Psalm 19 , begins "The heavens proclaim the glory of God, the firmament proclaims his handiwork", and likens the Sun to a bridegroom, to a warrior, and to the Torah . An Aggadic legend found in tractate Avodah Zarah 8a contains the talmudic hypothesis that Adam the first established the tradition of fasting before the winter solstice , and rejoicing afterward, which festival later devolved into

6985-403: 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

7112-404: The angular diameter of the Sun. Observing that it occurred within a two-day period is easier, requiring an observation precision of only about 1/16 of the angular diameter of the Sun. Thus, many observations are of the day of the solstice rather than the instant. This is often done by observing sunrise and sunset or using an astronomically aligned instrument that allows a ray of light to be cast on

7239-425: 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

7366-450: 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

7493-454: 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

7620-616: 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

7747-419: 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

SECTION 60

#1732766162396

7874-527: 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

8001-463: 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

8128-480: The country however persons engaged in agriculture may freely and lawfully continue their pursuits because it often happens that another day is not suitable for grain-sowing or vine planting; lest by neglecting the proper moment for such operations the bounty of heaven should be lost. Constantine's triumphal arch was carefully positioned to align with the colossal statue of Sol by the Colosseum , so that Sol formed

8255-539: 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

8382-512: The deity Elagabalus with Jupiter and Sol: fuit autem Heliogabali vel Iovis vel Solis sacerdos , "He was also a priest of Heliogabalus, or Jove , or Sol". While this has been seen as an attempt to import the Syrian sun god to Rome, the Roman cult of Sol had existed in Rome at least since the early Republic . The Roman gens Aurelia was associated with the cult of Sol. After his victories in

8509-482: The deity with the same name is unclear and perhaps non-existent. According to the Historia Augusta , Elagabalus , the teenaged Severan heir, adopted the name of his deity and brought his cult image from Emesa to Rome. Once installed as emperor, he neglected Rome's traditional State deities and promoted his own as Rome's most powerful deity. This ended with his murder in 222. The Historia Augusta equates

8636-490: The dominant backdrop when seen from the direction of the main approach towards the arch. Berrens (2004) deals with coin-evidence of Imperial connection to the Solar cult. Sol is depicted sporadically on imperial coins in the 1st and 2nd centuries AD, then more frequently from Septimius Severus onwards until AD 325–326. SOL INVICTUS appears on coin legends from AD 261, well before the reign of Aurelian. Connections between

8763-611: 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

8890-478: The early fourth century AD associates Christ's birth with the birthday of Sol Invictus: Our Lord, too, is born in the month of December ... the eighth before the calends of January [25 December] ... But they [the pagans] call it the ' Birthday of the Unconquered '. Who indeed is so unconquered as Our Lord? Or, if they say that it is the birthday of the Sun, [we may say] He is the Sun of Justice. The theory

9017-626: The emperor Aurelian instituted the festival Dies Natalis Solis Invicti ('birthday of the Invincible Sun') on 25 December, the date of the winter solstice in the Roman calendar. In Rome, this yearly festival was celebrated with thirty chariot races. Gary Forsythe, Professor of Ancient History, says "This celebration would have formed a welcome addition to the seven-day period of the Saturnalia (December 17–23), Rome's most joyous holiday season since Republican times, characterized by parties, banquets, and exchanges of gifts". In AD 362,

9144-626: The emperor Julian wrote in his Hymn to King Helios that the Agon Solis was a festival of the sun held at the end of the Saturnalia in late December. The festival is recorded in the Chronograph of 354 (or Filocalian calendar). Historians generally agree that this part of the text was written in Rome in AD 336. Wallraff (2001) says there is limited evidence for the festival before

9271-544: 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

9398-465: The first century CE. Sol Invictus , on the other hand, was believed to be a Syrian sun god whose cult was first promoted in Rome under Elagabalus , without success. Some fifty years later, in 274 CE, Aurelian established the cult of Sol Invictus as an official religion. There has never been consensus on which Syrian sun god he might have been: some scholars opted for the sky god of Emesa, Elagabal , while others preferred Malakbel of Palmyra . In

9525-638: 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

9652-404: 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

9779-598: The house, kinship or neighborhood, a practice performed in order to give strength to the Sun according to the old beliefs. The rites related to the cult of vegetation, which expressed the desire for increased production in agriculture and animal husbandry, were accompanied by animal sacrifices to the fire, lighting pine trees at night, luck divination tests with crackling in the fire or with coins in ritual bread, making and consuming ritual foods, performing various magical ritualistic actions in livestock, fields, vineyards and orchards, and so on. Nata e Buzmit, " Yule log 's night",

9906-472: The imperial radiate crown and the cult of Sol are postulated. Augustus was posthumously depicted with radiate crown, as were living emperors from Nero (after AD 65) to Constantine . Some modern scholarship interprets the imperial radiate crown as a divine, solar association rather than an overt symbol of Sol; Bergmann calls it a pseudo-object designed to disguise the divine and solar connotations that would otherwise be politically controversial but there

10033-406: 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

10160-513: 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

10287-399: 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

10414-410: 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

10541-456: 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

10668-497: 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

10795-409: 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

10922-483: 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

11049-417: 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

11176-612: 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

11303-468: The mid-4th century. A widely-held theory is that the Church chose December 25 as Jesus Christ's birthday ( Dies Natalis Christi ) to appropriate the festival of Sol Invictus's birthday Dies Natalis Solis Invicti , held on the same date. The early Church linked Jesus Christ to the Sun and referred to him as the 'Sun of Righteousness' ( Sol Justitiae ) prophesied by Malachi . A Christian treatise attributed to John Chrysostom and dating to

11430-548: 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

11557-491: The mosaic of Mausoleum M has been interpreted by some as Christ. Clement of Alexandria had spoken of Christ driving his chariot across the sky. This interpretation is doubted by others: "Only the cross-shaped nimbus makes the Christian significance apparent", and the figure is seen by some simply as a representation of the Sun with no explicit religious reference whatever, pagan or Christian. The traditional image of

11684-399: 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,

11811-424: 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

11938-425: 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

12065-593: 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

12192-670: 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

12319-528: 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

12446-649: 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

12573-474: 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

12700-501: 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

12827-406: The people were economically dependent on monitoring the progress of the seasons. Starvation was common during the first months of the winter, January to April (northern hemisphere) or July to October (southern hemisphere). Livestock were slaughtered so they would not have to be fed during the winter, so it was almost the only time of year when a plentiful supply of fresh meat was available. Because

12954-478: 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,

13081-400: 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

13208-421: 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

13335-461: The precise timing of its occurrence is now public knowledge. The precise instant of the solstice cannot be directly detected (by definition, people cannot observe that an object has stopped moving until it is later observed that it has not moved further from the preceding spot, or that it has moved in the opposite direction). To be precise to a single day, observers must be able to view a change in azimuth or elevation less than or equal to about 1/60 of

13462-495: 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

13589-538: The radiate crown of living emperors is a symbolic link to Augustus. His successors automatically inherited (or sometimes acquired) the same offices and honours due to Octavian as "saviour of the Republic" through his victory at Actium, piously attributed to Apollo - Helios . Furthermore, radiate crowns were not solely worn by emperors: The wreaths awarded to victors at the Actian Games were radiate. In AD 274,

13716-493: 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

13843-435: The revisionist view, there was only one cult of Sol in Rome, continuous from the monarchy to the end of antiquity . There were at least three temples of Sol in Rome, all active during the Empire and all dating from the earlier Republic. Invictus ("unconquered, invincible") was an epithet utilized for several Roman deities , including Jupiter , Mars , Hercules , Apollo , and Silvanus . It had been in use from

13970-575: The same period, a tradition that is originally related to the cult of the Sun. In East Asia , the winter solstice has been celebrated as one of the Twenty-four Solar Terms , called Dongzhi (冬至) in Chinese . In Japan , in order not to catch cold in the winter, there is a custom to soak oneself in a yuzu hot bath ( Japanese : 柚子湯 = Yuzuyu). Makara Sankranti, also known as Makara Sankrānti ( Sanskrit : मकर संक्रांति) or Maghi,

14097-437: The senatorial elite, indicating that the priesthood of Sol was now highly prestigious. Almost all these senators held other priesthoods as well, however, and some of these other priesthoods take precedence in the inscriptions in which they are listed, suggesting that they were considered more prestigious than the priesthood of Sol. Aurelian also built a new temple for Sol , which was dedicated on 25 December 274, and brought

14224-522: 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

14351-521: The sky. Each polar region experiences continuous darkness or twilight around its winter solstice. The opposite event is the summer solstice . The winter solstice occurs during the hemisphere's winter . In the Northern Hemisphere, this is the December solstice (December 21, December 22, or December 23) and in the Southern Hemisphere, this is the June solstice (June 20, June 21, or June 22). Although

14478-471: The summer and winter solstices exchanged and the spring and autumnal equinox dates swapped. Sol Invictus In recent years, the scholarly community has become divided on Sol between traditionalists and a growing group of revisionists. In the traditional view, Sol Invictus was the second of two different sun gods in Rome. The first of these, Sol Indiges , or Sol , was believed to be an early Roman god of minor importance whose cult had petered out by

14605-468: The sunrise or sunset on the winter solstice. There is evidence that the winter solstice was deemed an important moment of the annual cycle for some cultures as far back as the Neolithic (New Stone Age). Astronomical events were often used to guide farming activities, such as the mating of animals, the sowing of crops and the monitoring of winter reserves of food. The winter solstice was important because

14732-494: The total number of temples for the god in Rome to (at least) four. He also instituted games in honor of the sun god, held every four years from 274 onwards. The identity of Aurelian's Sol Invictus has long been a subject of scholarly debate. Based on the Augustan History , some scholars have argued that it was based on Sol Elagablus (or Elagabla) of Emesa . Others, basing their argument on Zosimus , suggest that it

14859-524: The winter solstice celebrate the return of the Sun ( Dielli ) for summer and the lengthening of the days. The Albanian traditional rites during the winter solstice period are pagan, and very ancient. Albanologist Johann Georg von Hahn (1811 – 1869) reported that Christian clergy, during his time and before, have vigorously fought the pagan rites that were practiced by Albanians to celebrate this festivity, but without success. The old rites of this festivity were accompanied by collective fires ( zjarre ) based on

14986-631: The winter solstice is the reversal of the Sun's apparent ebbing in the sky, in ancient times it was seen as the symbolic death and rebirth of the Sun or of a Sun god . In cultures which used cyclic calendars based on the winter solstice, the "year as reborn" was celebrated with reference to life-death-rebirth deities or "new beginnings" (such as Hogmanay 's redding , a New Year cleaning tradition), and "reversal" (as in Saturnalia 's slave and master reversals). Some important Neolithic and early Bronze Age archaeological sites in Europe are associated with

15113-416: The winter solstice itself lasts only a moment, the term also refers to the day on which it occurs. The term midwinter is also used synonymously with the winter solstice, although it carries other meanings as well. Traditionally, in many temperate regions, the winter solstice is seen as the middle of winter; although today in some countries and calendars it is seen as the beginning of winter. Other names are

15240-587: The winter solstice, and he saw that the day was continuously lengthening, he said, "It is the order of the world!" He went and feasted for eight days. The following year, he feasted for both. He established them in Heaven's name, but they established them in the name of idolatry Although the instant of the solstice can be calculated, direct observation of the moment by visual perception is elusive. The Sun moves too slowly or appears to stand still (the meaning of "solstice"). However, by use of astronomical data tracking ,

15367-590: The winter solstice, such as Stonehenge in England and Newgrange in Ireland. The primary axes of both of these monuments seem to have been carefully aligned on a sight-line pointing to the winter solstice sunrise (Newgrange) and the winter solstice sunset (Stonehenge). It is significant that at Stonehenge the Great Trilithon was oriented outwards from the middle of the monument, i.e. its smooth flat face

15494-461: 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

15621-551: The year". Yalda night celebration, or as some call it "Shabe Chelleh" ("the 40th night"), is one of the oldest Iranian traditions that has been present in Persian culture from ancient times. In this night all the family gather together, usually at the house of the eldest, and celebrate it by eating, drinking and reciting poetry (esp. Hafez). Nuts, pomegranates and watermelons are particularly served during this festival. An Aggadic legend found in tractate Avodah Zarah 8a puts forth

15748-620: 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

15875-633: Was a sun festival on the winter solstice. Modern scholars generally do not believe this, as midwinter in medieval Iceland was a date about four weeks after the solstice. During the Christianisation of the Germanic peoples , Yule was incorporated into the Christmas celebrations and the term and its cognates remain used to refer to Christmas in modern Northern European languages such as English and Swedish. Albanian traditional festivities around

16002-467: Was based on the Šams , the solar god of Palmyra on the grounds that Aurelian placed and consecrated a cult statue of the sun god looted from Palmyra in the temple of Sol Invictus. Forsythe (2012) discusses these arguments and adds a third more recent one, based on the work of Steven Hijmans. Hijmans argues that Aurelian's solar deity was simply the traditional Greco-Roman SOL INVICTUS . Emperors portrayed SOL INVICTUS on their official coinage, with

16129-414: Was turned towards the midwinter Sun. In the ancient Roman calendar, December 25 was the date of the winter solstice. In AD 274, the emperor Aurelian made this the date of the festival Dies Natalis Solis Invicti , the birthday of Sol Invictus or the 'Invincible Sun'. Gary Forsythe, Professor of Ancient History, says "This celebration would have formed a welcome addition to the seven-day period of

#395604