Astronomy:Location of Earth

From HandWiki
Short description: Knowledge of the location of Earth


Knowledge of the location of Earth has been shaped by 400 years of telescopic observations, and has expanded radically since the start of the 20th century. Initially, Earth was believed to be the center of the Universe, which consisted only of those planets visible with the naked eye and an outlying sphere of fixed stars.[1] After the acceptance of the heliocentric model in the 17th century, observations by William Herschel and others showed that the Sun lay within a vast, disc-shaped galaxy of stars.[2] By the 20th century, observations of spiral nebulae revealed that the Milky Way galaxy was one of billions in an expanding universe,[3][4] grouped into clusters and superclusters. By the end of the 20th century, the overall structure of the visible universe was becoming clearer, with superclusters forming into a vast web of filaments and voids.[5] Superclusters, filaments and voids are the largest coherent structures in the Universe that we can observe.[6] At still larger scales (over 1000 megaparsecs[lower-alpha 1]) the Universe becomes homogeneous, meaning that all its parts have on average the same density, composition and structure.[7]

Since there is believed to be no "center" or "edge" of the Universe, there is no particular reference point with which to plot the overall location of the Earth in the universe.[8] Because the observable universe is defined as that region of the Universe visible to terrestrial observers, Earth is, because of the constancy of the speed of light, the center of Earth's observable universe. Reference can be made to the Earth's position with respect to specific structures, which exist at various scales. It is still undetermined whether the Universe is infinite. There have been numerous hypotheses that the known universe may be only one such example within a higher multiverse; however, no direct evidence of any sort of multiverse has been observed, and some have argued that the hypothesis is not falsifiable.[9][10]

Details

Earth is the third planet from the Sun with an approximate distance of 149.6 million kilometres (93.0 million miles), and is traveling nearly 2.1 million kilometres per hour (1.3 million miles per hour) through outer space.[11]

Table

Feature Diameter Notes Sources
(most suitable unit) (km, with scientific notation) (km, as a power of 10, Logarithmic scale)
Earth 12,756.2 km
(equatorial) 		1.28×104 4.11 Measurement comprises just the solid part of the Earth; there is no agreed upper boundary for Earth's atmosphere.
The geocorona, a layer of UV-luminescent hydrogen atoms, lies at 100,000 km.
The Kármán line, defined as the boundary of space for astronautics, lies at 100 km.		 [12][13][14][15]
Orbit of the Moon 768,210 km[lower-alpha 2] 7.68×105 5.89 The average diameter of the orbit of the Moon relative to the Earth. [16]
Geospace 6,363,000–12,663,000 km
(110–210 Earth radii) 		6.36×106–1.27×107 6.80–7.10 The space dominated by Earth's magnetic field and its magnetotail, shaped by the solar wind. [17]
Earth's orbit 299.2 million km[lower-alpha 2]
2 AU[lower-alpha 3] 		2.99×108 8.48 The average diameter of the orbit of the Earth relative to the Sun.
Encompasses the Sun, Mercury and Venus.		 [18]
Inner Solar System ~6.54 AU 9.78×108 8.99 Encompasses the Sun, the inner planets (Mercury, Venus, Earth, Mars) and the asteroid belt.
Cited distance is the 2:1 resonance with Jupiter, which marks the outer limit of the asteroid belt.		 [19][20][21]
Outer Solar System 60.14 AU 9.00×109 9.95 Includes the outer planets (Jupiter, Saturn, Uranus, Neptune).
Cited distance is the orbital diameter of Neptune.		 [22]
Kuiper belt ~96 AU 1.44×1010 10.16 Belt of icy objects surrounding the outer Solar System. Encompasses the dwarf planets Pluto, Haumea and Makemake.
Cited distance is the 2:1 resonance with Neptune, generally regarded as the outer edge of the main Kuiper belt.		 [23]
Heliosphere 160 AU 2.39×1010 10.38 Maximum extent of the solar wind and the interplanetary medium. [24][25]
Scattered disc 195.3 AU 2.92×1010 10.47 Region of sparsely scattered icy objects surrounding the Kuiper belt. Encompasses the dwarf planet Eris.
Cited distance is derived by doubling the aphelion of Eris, the farthest known scattered disc object.
As of now, Eris's aphelion marks the farthest known point in the scattered disc.		 [26]
Oort cloud 100,000–200,000 AU
0.613–1.23 pc[lower-alpha 1] 		1.89×1013–3.80×1013 13.28–13.58 Spherical shell of over a trillion (1012) comets. Existence is currently hypothetical, but inferred from the orbits of long-period comets. [27]
Solar System 1.23 pc 3.80×1013 13.58 The Sun and its planetary system. Cited diameter is that of the Sun's Hill sphere; the region of its gravitational influence. [28]
Local Interstellar Cloud 9.2 pc 2.84×1014 14.45 Interstellar cloud of gas through which the Sun and a number of other stars are currently travelling. [29]
Local Bubble 2.82–250 pc 8.70×1013–7.71×1015 13.94–15.89 Cavity in the interstellar medium in which the Sun and a number of other stars are currently travelling.
Caused by a past supernova.		 [30][31]
Gould Belt 1,000 pc 3.09×1016 16.49 Projection effect of the Radcliffe wave and Split linear structures (Gould Belt),[32] between which the Sun is currently travelling. [33]
Orion Arm 3000 pc
(length) 		9.26×1016 16.97 The spiral arm of the Milky Way Galaxy through which the Sun is currently travelling.
Orbit of the Solar System 17,200 pc 5.31×1017 17.72 The average diameter of the orbit of the Solar System relative to the Galactic Center.
The Sun's orbital radius is roughly 8,600 parsecs, or slightly over half way to the galactic edge.
One orbital period of the Solar System lasts between 225 and 250 million years.		 [34][35]
Milky Way Galaxy 30,000 pc 9.26×1017 17.97 Our home galaxy, composed of 200 billion to 400 billion stars and filled with the interstellar medium. [36][37]
Milky Way subgroup 840,500 pc 2.59×1019 19.41 The Milky Way and those satellite dwarf galaxies gravitationally bound to it.
Examples include the Sagittarius Dwarf, the Ursa Minor Dwarf and the Canis Major Dwarf.
Cited distance is the orbital diameter of the Leo T Dwarf galaxy, the most distant galaxy in the Milky Way subgroup. Currently 59 satellite galaxies are part of the subgroup.		 [38]
Local Group 3 Mpc[lower-alpha 1] 9.26×1019 19.97 Group of at least 80 galaxies of which the Milky Way is a part.
Dominated by Andromeda (the largest), the Milky Way and Triangulum; the remainder are dwarf galaxies.		 [39]
Local Sheet 7 Mpc 2.16×1020 20.33 Group of galaxies including the Local Group moving at the same relative velocity towards the Virgo Cluster and away from the Local Void. [40][41]
Virgo Supercluster 30 Mpc 9.26×1020 20.97 The supercluster of which the Local Group is a part.
It comprises roughly 100 galaxy groups and clusters, centred on the Virgo Cluster.
The Local Group is located on the outer edge of the Virgo Supercluster.		 [42][43]
Laniakea Supercluster 160 Mpc 4.94×1021 21.69 A group connected with the superclusters of which the Local Group is a part.
Comprises roughly 300 to 500 galaxy groups and clusters, centred on the Great Attractor in the Hydra–Centaurus Supercluster.		 [44][45][46][47]
Pisces–Cetus Supercluster Complex 330 Mpc 1×1022 21.98 Galaxy filament that includes the Pisces-Cetus Superclusters, Perseus–Pisces Supercluster, Sculptor Supercluster and associated smaller filamentary chains. [48][49]
Observable Universe 28,500 Mpc 8.79×1023 23.94 At least 2 trillion galaxies in the observable universe, arranged in millions of superclusters, galactic filaments, and voids, creating a foam-like superstructure. [50][51][52][53]
Universe Minimum 28,500 Mpc
(possibly infinite) 		Minimum 8.79×1023 Minimum 23.94 Beyond the observable universe lie the unobservable regions from which no light has yet reached the Earth.
No information is available, as light is the fastest travelling medium of information.
However, uniformitarianism argues that the Universe is likely to contain more galaxies in the same foam-like superstructure.		 [54]

Gallery

Logarithmic depiction of Earth's location
Location of the Earth in the Universe
Earth-Moon System
Inner Solar System with Near-Earth objects
Solar System and Oort cloud
Nearest stars
Local Interstellar Cloud and neighbouring interstellar medium
Star associations and interstellar medium map of the Local Bubble
Molecular clouds around the Sun inside the Orion-Cygnus Arm
Orion-Cygnus Arm and neighbouring arms
Orion-Cygnus Arm inside the Milky Way
The Sun within the structure of the Milky Way
Satellite galaxies of the Milky Way in Local Group
Virgo SCl in Laniakea SCl
Laniakea SCl in Pisces–Cetus Supercluster Complex
Observable Universe of the Universe


A logarithmic map of the observable universe. From left to right, spacecraft and celestial bodies are arranged according to their proximity to the Earth.
A logarithmic map of the observable universe. From left to right, spacecraft and celestial bodies are arranged according to their proximity to the Earth.
A logarithmic map of the observable universe. From left to right, spacecraft and celestial bodies are arranged according to their proximity to the Earth.
A logarithmic map of the observable universe. From left to right, spacecraft and celestial bodies are arranged according to their proximity to the Earth.
Stereoscopic view of the universe (805 x 416) for cross-eyed viewing

See also


Notes

  1. ↑ 1.0 1.1 1.2 A parsec (pc) is the distance at which a star's parallax as viewed from Earth is equal to one second of arc, equal to roughly 206,000 AU or 3.0857×1013 km. One megaparsec (Mpc) is equivalent to one million parsecs.
  2. ↑ 2.0 2.1 Semi-major and semi-minor axes.
  3. ↑ 1 AU or astronomical unit is the distance between the Earth and the Sun, or 150 million km. Earth's orbital diameter is twice its orbital radius, or 2 AU.

References

  1. ↑ Kuhn, Thomas S. (1957). The Copernican Revolution. Harvard University Press. pp. 5–20. ISBN 978-0-674-17103-9. https://archive.org/details/copernicanrevolu0008kuhn. 
  2. ↑ "1781: William Herschel Reveals the Shape of our Galaxy". Carnegie Institution for Science. http://cosmology.carnegiescience.edu/timeline/1781. 
  3. ↑ "The Spiral Nebulae and the Great Debate". Eberly College of Science. https://www.e-education.psu.edu/astro801/content/l9_p2.html. 
  4. ↑ "1929: Edwin Hubble Discovers the Universe is Expanding". Carnegie Institution for Science. https://cosmology.carnegiescience.edu/timeline/1929. 
  5. ↑ "1989: Margaret Geller and John Huchra Map the Universe". Carnegie Institution for Science. https://cosmology.carnegiescience.edu/timeline/1989. 
  6. ↑ Villanueva, John Carl (2009). "Structure of the Universe". Universe Today. http://www.universetoday.com/37360/structure-of-the-universe/. 
  7. ↑ Kirshner, Robert P. (2002). The Extravagant Universe: Exploding Stars, Dark Energy and the Accelerating Cosmos. Princeton University Press. p. 71. ISBN 978-0-691-05862-7. https://archive.org/details/extravagantunive00kirs. 
  8. ↑ Mainzer, Klaus; Eisinger, J. (2002). The Little Book of Time. Springer. p. 55. ISBN 978-0-387-95288-8. https://books.google.com/books?id=wX111YnexSUC&pg=PA55. 
  9. ↑ Moskowitz, Clara (2012). "5 Reasons We May Live in a Multiverse". space.com. http://www.space.com/18811-multiple-universes-5-theories.html. 
  10. ↑ Kragh, H. (2009). "Contemporary History of Cosmology and the Controversy over the Multiverse". Annals of Science 66 (4): 529–551. doi:10.1080/00033790903047725. 
  11. ↑ Fraknoi, Andrew (2007). "How Fast Are You Moving When You Are Sitting Still?". NASA. https://nightsky.jpl.nasa.gov/docs/HowFast.pdf. 
    NOTE: Estimated velocity of the Earth traveling through outer space may be between 1.3–3.1 million kilometres per hour (0.8–1.9 million miles per hour) – see discussion at "Wikipedia:Reference desk/Archives/Science/2019 July 20#How fast are we moving through space?"
  12. ↑ "Selected Astronomical Constants, 2011". The Astronomical Almanac. http://asa.usno.navy.mil/SecK/2011/Astronomical_Constants_2011.txt. 
  13. ↑ World Geodetic System (WGS-84). Available online from National Geospatial-Intelligence Agency Retrieved 27 April 2015.
  14. ↑ "Exosphere – overview". University Corporation for Atmospheric Research. 2011. http://scied.ucar.edu/shortcontent/exosphere-overview. 
  15. ↑ S. Sanz Fernández de Córdoba (24 June 2004). "The 100 km Boundary for Astronautics". Fédération Aéronautique Internationale. http://www.fai.org/icare-records/100km-altitude-boundary-for-astronautics. 
  16. ↑ NASA Moon Factsheet and NASA Solar System Exploration Moon Factsheet NASA Retrieved on 17 November 2008
  17. ↑ Koskinen, Hannu (2010), Physics of Space Storms: From the Surface of the Sun to the Earth, Environmental Sciences Series, Springer, ISBN 978-3-642-00310-3, https://books.google.com/books?id=cO0nwfhXVjUC&pg=PA32 
  18. ↑ "Earth Fact Sheet". NASA. http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html.  and "Earth: Facts & Figures". NASA. http://sse.jpl.nasa.gov/planets/profile.cfm?Object=Earth&Display=Facts&System=Metric. 
  19. ↑ Petit, J.-M.; Morbidelli, A.; Chambers, J. (2001). "The Primordial Excitation and Clearing of the Asteroid Belt". Icarus 153 (2): 338–347. doi:10.1006/icar.2001.6702. Bibcode: 2001Icar..153..338P. http://www.gps.caltech.edu/classes/ge133/reading/asteroids.pdf. Retrieved 22 March 2007. 
  20. ↑ Roig, F.; Nesvorný, D.; Ferraz-Mello, S. (2002). "Asteroids in the 2 : 1 resonance with Jupiter: dynamics and size distribution". Monthly Notices of the Royal Astronomical Society 335 (2): 417–431. doi:10.1046/j.1365-8711.2002.05635.x. Bibcode: 2002MNRAS.335..417R. 
  21. ↑ Brož, M; Vokrouhlický, D; Roig, F; Nesvorný, D; Bottke, W. F; Morbidelli, A (2005). "Yarkovsky origin of the unstable asteroids in the 2/1 mean motionresonance with Jupiter". Monthly Notices of the Royal Astronomical Society 359 (4): 1437–1455. doi:10.1111/j.1365-2966.2005.08995.x. Bibcode: 2005MNRAS.359.1437B. 
  22. ↑ NASA Neptune factsheet and NASA Solar System Exploration Neptune Factsheet NASA Retrieved on 17 November 2008
  23. ↑ De Sanctis, M. C; Capria, M. T; Coradini, A (2001). "Thermal Evolution and Differentiation of Edgeworth–Kuiper Belt Objects". The Astronomical Journal 121 (5): 2792–2799. doi:10.1086/320385. Bibcode: 2001AJ....121.2792D. 
  24. ↑ NASA/JPL (2009). "Cassini's Big Sky: The View from the Center of Our Solar System". http://www.jpl.nasa.gov/news/features.cfm?feature=2370&msource=F20091119&tr=y&auid=5615216. 
  25. ↑ Fahr, H. J.; Kausch, T.; Scherer, H. (2000). "A 5-fluid hydrodynamic approach to model the Solar System-interstellar medium interaction". Astronomy & Astrophysics 357: 268. Bibcode: 2000A&A...357..268F. http://aa.springer.de/papers/0357001/2300268.pdf. Retrieved 3 October 2009.  See Figures 1 and 2.
  26. ↑ "JPL Small-Body Database Browser: 136199 Eris (2003 UB313)". http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=Eris. 
  27. ↑ Morbidelli, Alessandro (2005). "Origin and dynamical evolution of comets and their reservoir". arXiv:astro-ph/0512256.
  28. ↑ Littmann, Mark (2004). Planets Beyond: Discovering the Outer Solar System. Courier Dover Publications. pp. 162–163. ISBN 978-0-486-43602-9. https://archive.org/details/planetsbeyonddis00mlit. 
  29. ↑ Mark Anderson, "Don't stop till you get to the Fluff", New Scientist no. 2585, 6 January 2007, pp. 26–30
  30. ↑ Seifr, D.M. (1999). "Mapping the Countours of the Local Bubble". Astronomy and Astrophysics 346: 785–797. Bibcode: 1999A&A...346..785S. 
  31. ↑ Phillips, Tony (2014). "Evidence for Supernovas Near Earth". NASA. https://science.nasa.gov/science-news/science-at-nasa/2014/26aug_localbubble/. 
  32. ↑ Alves, João; Zucker, Catherine; Goodman, Alyssa A.; Speagle, Joshua S.; Meingast, Stefan; Robitaille, Thomas; Finkbeiner, Douglas P.; Schlafly, Edward F. et al. (23 January 2020). "A Galactic-scale gas wave in the Solar Neighborhood". Nature 578 (7794): 237–239. doi:10.1038/s41586-019-1874-z. PMID 31910431. Bibcode: 2020Natur.578..237A. 
  33. ↑ Popov, S. B; Colpi, M; Prokhorov, M. E; Treves, A; Turolla, R (2003). "Young isolated neutron stars from the Gould Belt". Astronomy and Astrophysics 406 (1): 111–117. doi:10.1051/0004-6361:20030680. Bibcode: 2003A&A...406..111P. 
  34. ↑ Eisenhauer, F.; Schoedel, R.; Genzel, R.; Ott, T.; Tecza, M.; Abuter, R.; Eckart, A.; Alexander, T. (2003). "A Geometric Determination of the Distance to the Galactic Center". Astrophysical Journal 597 (2): L121–L124. doi:10.1086/380188. Bibcode: 2003ApJ...597L.121E. 
  35. ↑ Leong, Stacy (2002). "Period of the Sun's Orbit around the Galaxy (Cosmic Year)". The Physics Factbook. http://hypertextbook.com/facts/2002/StacyLeong.shtml. 
  36. ↑ Christian, Eric; Samar, Safi-Harb. "How large is the Milky Way?". NASA. http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980317b.html. 
  37. ↑ "The Milky Way Galaxy". SEDS. 25 August 2005. http://messier.seds.org/more/mw.html. 
  38. ↑ Irwin, V. et al. (2007). "Discovery of an Unusual Dwarf Galaxy in the Outskirts of the Milky Way". The Astrophysical Journal 656 (1): L13–L16. doi:10.1086/512183. Bibcode: 2007ApJ...656L..13I. 
  39. ↑ "The Local Group of Galaxies". University of Arizona. Students for the Exploration and Development of Space. http://messier.seds.org/more/local.html. 
  40. ↑ Tully, R. Brent; Shaya, Edward J.; Karachentsev, Igor D.; Courtois, Hélène M.; Kocevski, Dale D.; Rizzi, Luca; Peel, Alan (March 2008). "Our Peculiar Motion Away from the Local Void". The Astrophysical Journal 676 (1): 184–205. doi:10.1086/527428. Bibcode: 2008ApJ...676..184T. 
  41. ↑ Tully, R. Brent (May 2008). "The Local Void is Really Empty". Dark Galaxies and Lost Baryons, Proceedings of the International Astronomical Union, IAU Symposium. 244. 146–151. doi:10.1017/S1743921307013932. Bibcode: 2008IAUS..244..146T. 
  42. ↑ Tully, R. Brent (1982). "The Local Supercluster". The Astrophysical Journal 257: 389–422. doi:10.1086/159999. Bibcode: 1982ApJ...257..389T. 
  43. ↑ "Galaxies, Clusters, and Superclusters". NOVA Online. https://www.pbs.org/wgbh/nova/universe/tour_ggs.html. 
  44. ↑ "Newly identified galactic supercluster is home to the Milky Way". National Radio Astronomy Observatory (ScienceDaily). 3 September 2014. https://www.sciencedaily.com/releases/2014/09/140903133319.htm. 
  45. ↑ Klotz, Irene (3 September 2014). "New map shows Milky Way lives in Laniakea galaxy complex". Reuters. ScienceDaily. https://www.reuters.com/article/us-space-galaxies-idUSKBN0GY2C820140903. 
  46. ↑ Gibney, Elizabeth (3 September 2014). "Earth's new address: 'Solar System, Milky Way, Laniakea'". Nature. doi:10.1038/nature.2014.15819. http://www.nature.com/news/earth-s-new-address-solar-system-milky-way-laniakea-1.15819. 
  47. ↑ Carlisle, Camille M. (3 September 2014). "Laniakea: Our Home Supercluster". Sky and Telescope. http://www.skyandtelescope.com/astronomy-news/laniakea-home-supercluster-09032014/. 
  48. ↑ Tully, R. B. (1986-04-01). "Alignment of clusters and galaxies on scales up to 0.1 C". The Astrophysical Journal 303: 25–38. doi:10.1086/164049. Bibcode: 1986ApJ...303...25T. 
  49. ↑ Tully, R. Brent (1987-12-01). "More about clustering on a scale of 0.1 C". The Astrophysical Journal 323: 1–18. doi:10.1086/165803. Bibcode: 1987ApJ...323....1T. 
  50. ↑ Mackie, Glen (1 February 2002). "To see the Universe in a Grain of Taranaki Sand". Swinburne University. http://astronomy.swin.edu.au/~gmackie/billions.html. 
  51. ↑ Lineweaver, Charles; Davis, Tamara M. (2005). "Misconceptions about the Big Bang". Scientific American. http://www.sciam.com/article.cfm?id=misconceptions-about-the-2005-03&page=5. Retrieved 6 November 2008. 
  52. ↑ Conselice, Christopher J.; Wilkinson, Aaron; Duncan, Kenneth; Mortlock, Alice (13 October 2016). "The Evolution of Galaxy Number Density at z < 8 and its Implications". The Astrophysical Journal 830 (2): 83. doi:10.3847/0004-637X/830/2/83. ISSN 1538-4357. Bibcode: 2016ApJ...830...83C. 
  53. ↑ "Two Trillion Galaxies, at the Very Least". The New York Times. 17 October 2016. https://www.nytimes.com/2016/10/18/science/two-trillion-galaxies-at-the-very-least.html. 
  54. ↑ Margalef-Bentabol, Berta; Margalef-Bentabol, Juan; Cepa, Jordi (February 2013). "Evolution of the cosmological horizons in a universe with countably infinitely many state equations". Journal of Cosmology and Astroparticle Physics. 015 2013 (2): 015. doi:10.1088/1475-7516/2013/02/015. Bibcode: 2013JCAP...02..015M. 



Retrieved from "https://handwiki.org/wiki/index.php?title=Astronomy:Location_of_Earth&oldid=3348342"