Yird

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Earth Astronomical seembol o Yird
The Earth seen from Apollo 17.jpg
The Blue Marble photograph o Yird, taken during the Apollo 17 lunar mission in 1972
Orbital characteristics
Epoch J2000[n 1]
Aphelion 152100000 km[n 2]
(94500000 mi; 1.017 AU)
Perihelion 147095000 km[n 2]
(91401000 mi; 0.98327 AU)
Semi-major axis 149598023 km[1]
(92955902 mi; 1.00000102 AU)
Eccentricity 0.0167086[1]
Orbital period 365.256363004 d[2]
(1.00001742096 yr)
Average orbital speed 29.78 km/s[3]
(107200 km/h; 66600 mph)
Mean anomaly 358.617°
Inclination
Longitude o ascendin node −11.26064°[3] tae J2000 ecliptic
Argument o perihelion 114.20783°[3]
Satellites
Pheesical characteristics
Mean radius 6371.0 km (3958.8 mi)[6]
Equatorial radius 6378.1 km (3963.2 mi)[7][8]
Polar radius 6356.8 km (3949.9 mi)[9]
Circumference
Surface aurie
  • 510072000 km2 (196940000 sq mi)[16][17][n 4]
  • 148940000 km2 laund (57510000 sq mi; 29.2%)
  • 361132000 km2 watter (139434000 sq mi; 70.8%)
Vollum 1.08321×1012 km3 (2.59876×1011 cu mi)[3]
Mass 5.97237×1024 kg (1.31668×1025 lb)[12]
(3.0×10−6 M)
Mean density 5.514 g/cm3 (0.1992 lb/cu in)[3]
Equatorial surface gravity 9.807 m/s2 (g; 32.18 ft/s2)[13]
Escape velocity 11.186 km/s[3]
(40270 km/h; 25020 mph)
Sidereal rotation period
0.99726968 d[14]
(23h 56m 4.100s)
Equatorial rotation velocity 1674.4 km/h[15]
(0.4651 km/s; 1674.4 km/h; 1040.4 mph)
Axial tilt 23.4392811°[2]
Albedo
Surface temp. min mean max
Kelvin 184 K[18] 288 K[19] 330 K[20]
Celsius −89.2 °C 15 °C 56.7 °C
Atmosphere
Surface pressur 101.325 kPa (at MSL)
Composeetion

Yird, itherwise kent as the Warld or the Globe, is the third planet frae the Sun an the anerly object in the Universe kent tae herbour life. It is the densest planet in the Solar Seestem an the lairgest o the fower terrestrial planets.

Accordin tae radiometric datin an ither soorces o evidence, Yird formed aboot 4.54 billion years aby.[22][23][24] Yird's gravity interacts wi ither objects in space, especially the Sun an the Muin, Yird's anerly naitural satellite. In ane orbit aroond the Sun, Yird rotates aboot its axis ower 365 times; thus, an Yird year is aboot 365.26 days lang.[n 5] Yird's axis o rotation is tilted, producin saisonal variations on the planet's surface.[25] The gravitational interaction atween the Yird an Muin causes ocean tides, stabilizes the Yird's orientation on its axis, an gradually slaws its rotation.[26]

Yird's lithosphere is dividit intae several rigid tectonic plates that migrate athort the surface ower periods o mony millions o years. Aboot 71% o Yird's surface is covered wi watter, maistly bi its oceans.[27] The remeenin 29% is laund conseestin o continents an islands that thegither hae mony lochs, rivers an ither soorces o watter that contreibute tae the hydrosphere. The majority o Yird's polar regions are covered in ice, includin the Antarctic ice sheet an the sea ice o the Arctic ice pack. Yird's interior remeens active wi a solit airn inner core, a liquid ooter core that generates the Yird's magnetic field, an a convectin mantle that drives plate tectonics.

Accordin tae scientists, within the first billion years o Yird's history, life appeared in the oceans an began tae affect the Yird's atmosphere an surface, leadin tae the proliferation o aerobic an anaerobic organisms. Some geological evidence indicates that life mey hae arisen as muckle as 4.1 billion years aby. Syne then, the combination o Yird's distance frae the Sun, pheesical properties, an geological history hae allaed life tae evolve an thrive.[28][29] In the history o the Yird, biodiversity haes gane throu lang periods o expansion, occasionally punctuatit bi mass extinction events. Ower 99% o aw species[30] that ever leeved on Yird are extinct.[31][32] Estimates o the nummer o species on Yird theday vary widely;[33][34][35] maist species hae nae been descrived.[36] Ower 7.4 billion humans leeve on Yird an depend on its biosphere an meenerals for thair survival. Humans hae developed diverse societies an culturs; poleetically, the warld has aboot 200 sovereign states.

See an aw[eedit | eedit soorce]

Notes[eedit | eedit soorce]

  1. Aw astronomical quantities vary, baith secularly an periodically. The quantities gien are the values at the instant J2000.0 o the secular variation, ignorin aw periodic variations.
  2. 2.0 2.1 aphelion = a × (1 + e); perihelion = a × (1 – e), whaur a is the semi-major axis an e is the eccentricity. The difference atween Yird's perihelion an aphelion is 5 million kilometres.
  3. As o Julie 5, 2016, the Unitit States Strategic Command tracked a tot o 17,729 airtifeecial objects, maistly debris. See: "Orbital Debris Quarterly News" (PDF). Vol. 20 no. 3. NASA. Julie 2016. p. 8. Retrieved 10 October 2016. 
  4. Due tae naitural fluctuations, ambiguities surroondin ice shelfs, an mappin conventions for vertical datums, exact values for laund an ocean coverage are nae meaninfu. Based on data frae the Vector Map an Global Landcover datasets, extreme values for coverage o lochs an streams are 0.6% an 1.0% o Yird's surface. The ice shields o Antarcticae an Greenland are coontit as land, even tho much o the rock that supports them lies ablo sea level.
  5. The nummer o solar days is ane less nor the nummer o sidereal days acause the orbital motion o Yird aroond the Sun causes ane addeetional revolution o the planet aboot its axis.

References[eedit | eedit soorce]

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  2. 2.0 2.1 Staff (7 August 2007). "Useful Constants". International Earth Rotation and Reference Systems Service. Retrieved 23 September 2008. 
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 Williams, David R. (1 September 2004). "Earth Fact Sheet". NASA. Retrieved 9 August 2010. 
  4. Allen, Clabon Walter; Cox, Arthur N. (2000). Allen's Astrophysical Quantities. Springer. p. 294. ISBN 0-387-98746-0. Retrieved 13 Mairch 2011. 
  5. "UCS Satellite Database". Nuclear Weapons & Global Security. Union of Concerned Scientists. 11 August 2016. Retrieved 10 October 2016. 
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