Earth's location in the universe - AbsoluteAstronomy.com

Knowledge of Earth's location in the universe has been shaped by 400 years of telescopic observations, and has expanded radically in the last century. Initially, Earth was believed to be the center of the universe

Geocentric model

In astronomy, the geocentric model , is the superseded theory that the Earth is the center of the universe, and that all other objects orbit around it. This geocentric model served as the predominant cosmological system in many ancient civilizations such as ancient Greece...

, which consisted only of those planets visible with the naked eye and an outlying sphere of fixed stars. After the acceptance of the heliocentric model in the 17th century, observations by William Herschel

William Herschel

Sir Frederick William Herschel, KH, FRS, German: Friedrich Wilhelm Herschel was a German-born British astronomer, technical expert, and composer. Born in Hanover, Wilhelm first followed his father into the Military Band of Hanover, but emigrated to Britain at age 19...

and others showed that Earth's Sun lay within a vast, disc-shaped galaxy

Galaxy

A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...

of stars, later revealed to be suns like our own. By the 20th century, observations of spiral nebulae revealed that our galaxy was only one of billions in an expanding universe, grouped into clusters and supercluster

Supercluster

Superclusters are large groups of smaller galaxy groups and clusters and are among the largest known structures of the cosmos. They are so large that they are not gravitationally bound and, consequently, partake in the Hubble expansion.-Existence:...

s. By the 21st century, the overall structure of the visible universe was becoming clearer, with superclusters forming into a vast web of filaments and voids

Void (astronomy)

In astronomy, voids are the empty spaces between filaments, the largest-scale structures in the Universe, that contain very few, or no, galaxies. They were first discovered in 1978 during a pioneering study by Stephen Gregory and Laird A. Thompson at the Kitt Peak National Observatory...

. Superclusters, filaments and voids are likely the largest coherent structures that exist in the Universe. At still larger scales (over 1000 megaparsecs) the Universe becomes homogeneous meaning that all its parts have on average the same density, composition and structure.

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. The Earth is at the center of the observable universe

Observable universe

In Big Bang cosmology, the observable universe consists of the galaxies and other matter that we can in principle observe from Earth in the present day, because light from those objects has had time to reach us since the beginning of the cosmological expansion...

because its observability is determined by its distance from Earth. 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, and there is speculation that our universe might only be one of countless trillions within a larger multiverse

Multiverse

The multiverse is the hypothetical set of multiple possible universes that together comprise all of reality.Multiverse may also refer to:-In fiction:* Multiverse , the fictional multiverse used by DC Comics...

, itself contained within the omniverse

Omniverse

The Omniverse is the conceptual ensemble of all possible universes, with all possible laws of physics.In this physical cosmology context, the limitation of the definition of "universe" that it has only one set of "physical laws and constants that govern them," is expanded to include multiple sets...

Earth in the Universe
Feature	Size	Notes	Sources
Earth Earth Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...	12,700 km in diameter	Our planet Planet A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,... .
Geospace	63,000 km Sunward side; 6,300,000 km trailing side	The space dominated by Earth's magnetic field Earth's magnetic field Earth's magnetic field is the magnetic field that extends from the Earth's inner core to where it meets the solar wind, a stream of energetic particles emanating from the Sun... .
Orbit of the Moon	770,000 km across	The average diameter of the orbit of the Moon relative to the Earth.
Earth's orbit Earth's orbit In astronomy, the Earth's orbit is the motion of the Earth around the Sun, at an average distance of about 150 million kilometers, every 365.256363 mean solar days .A solar day is on average 24 hours; it takes 365.256363 of these to orbit the sun once in the sense of returning...	300 million km across 2 AU Astronomical unit An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....	The average diameter of the orbit of the Earth relative to the Sun. Contains the Sun Sun The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields... , Mercury Mercury (planet) Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 87.969 Earth days. The orbit of Mercury has the highest eccentricity of all the Solar System planets, and it has the smallest axial tilt. It completes three rotations about its axis for every two orbits... and Venus Venus Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows... .
Inner Solar System	6 AU across	Contains the Sun, the inner planets (Mercury, Venus, Earth, Mars Mars Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance... ) and the asteroid belt Asteroid belt The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets... .
Outer Solar System	60 AU across	Surrounds the inner Solar System; comprises the outer planets Outer planets The outer planets are those planets in the Solar System beyond the asteroid belt, which typically refers to these gas giant planets in order of their distance from the Sun:... (Jupiter Jupiter Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,... , Saturn Saturn Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,... , Uranus Uranus Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus , the father of Cronus and grandfather of Zeus... , Neptune Neptune Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times... ).
Kuiper belt Kuiper belt The Kuiper belt , sometimes called the Edgeworth–Kuiper belt, is a region of the Solar System beyond the planets extending from the orbit of Neptune to approximately 50 AU from the Sun. It is similar to the asteroid belt, although it is far larger—20 times as wide and 20 to 200 times as massive...	96 AU across	Belt of icy objects surrounding the outer solar system. Contains the dwarf planet Dwarf planet A dwarf planet, as defined by the International Astronomical Union , is a celestial body orbiting the Sun that is massive enough to be spherical as a result of its own gravity but has not cleared its neighboring region of planetesimals and is not a satellite... s Pluto Pluto Pluto, formal designation 134340 Pluto, is the second-most-massive known dwarf planet in the Solar System and the tenth-most-massive body observed directly orbiting the Sun... , Haumea and Makemake.
Heliosphere Heliosphere The heliosphere is a bubble in space "blown" into the interstellar medium by the solar wind. Although electrically neutral atoms from interstellar volume can penetrate this bubble, virtually all of the material in the heliosphere emanates from the Sun itself...	160 AU across	Maximum extent of the Solar wind Solar wind The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time... and the interplanetary medium Interplanetary medium The interplanetary medium is the material which fills the solar system and through which all the larger solar system bodies such as planets, asteroids and comets move.-Composition and physical characteristics:... .
Scattered disk	200 AU across	Region of sparsely scattered icy objects surrounding the Kuiper belt. Contains the dwarf planet Eris Eris (dwarf planet) Eris, formal designation 136199 Eris, is the most massive known dwarf planet in the Solar System and the ninth most massive body known to orbit the Sun directly... .
Oort cloud Oort cloud The Oort cloud , or the Öpik–Oort cloud , is a hypothesized spherical cloud of comets which may lie roughly 50,000 AU, or nearly a light-year, from the Sun. This places the cloud at nearly a quarter of the distance to Proxima Centauri, the nearest star to the Sun...	100,000-200,000 AU across 2-4 light-year Light-year A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres... s	Spherical shell of over a trillion comet Comet A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet... s.
Solar System Solar System The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...	4 light-years across	Our home planetary system Planetary system A planetary system consists of the various non-stellar objects orbiting a star such as planets, dwarf planets , asteroids, meteoroids, comets, and cosmic dust... . At this point, the Sun's gravity gives way to that of surrounding stars.
Local Interstellar Cloud Local Interstellar Cloud The Local Interstellar Cloud is the interstellar cloud roughly 30 light years across through which the Earth's solar system is currently moving. The Solar System is thought to have entered the Local Interstellar Cloud at some time between 44,000 and 150,000 years ago and is expected to remain...	30 light-years across	Interstellar cloud Interstellar cloud Interstellar cloud is the generic name given to an accumulation of gas, plasma and dust in our and other galaxies. Put differently, an interstellar cloud is a denser-than-average region of the interstellar medium. Depending on the density, size and temperature of a given cloud, the hydrogen in it... of gas through which the Sun and a number of other stars are currently travelling.
Local Bubble Local Bubble The Local Bubble is a cavity in the interstellar medium of the Orion Arm of the Milky Way. It is at least 300 light years across and has a neutral hydrogen density of about 0.05 atoms per cubic centimetre, or approximately one tenth of the average for the ISM in the Milky Way , and half that for...	210-815 light-years across	Cavity in the interstellar medium Interstellar medium In astronomy, the interstellar medium is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, dust, and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space... in which our Sun and a number of other stars are currently travelling. Caused by a past supernova Supernova A supernova is a stellar explosion that is more energetic than a nova. It is pronounced with the plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months... .
Gould Belt Gould Belt The Gould Belt is a partial ring of stars in the Milky Way galaxy, about 3000 light years across, tilted toward the galactic plane by about 16 to 20 degrees. It contains many spectral class O- and B-type stars, and may represent the local spiral arm to which the Sun belongs—currently the Sun is...	3,000 light-years across	Ring of young stars through which our Sun is currently travelling.
Orion Arm Orion Arm The Orion–Cygnus Arm is a minor spiral arm of the Milky Way galaxy some 3,500 light years across and approximately 10,000 light years in length. The Solar System is within the Orion–Cygnus Arm...	10,000 light-years in length	The spiral arm of the Milky Way Galaxy through which our Sun is currently travelling.
Orbit of the Solar System Galactic year The galactic year, also known as a cosmic year, is the duration of time required for the Solar System to orbit once around the center of the Milky Way Galaxy. Estimates of the length of one orbit range from 225 to 250 million "terrestrial" years....	56,000 light years across	The average diameter of the orbit of the Solar System relative to the Galactic Center Galactic Center The Galactic Center is the rotational center of the Milky Way galaxy. It is located at a distance of 8.33±0.35 kpc from the Earth in the direction of the constellations Sagittarius, Ophiuchus, and Scorpius where the Milky Way appears brightest... . Our Sun's orbital radius is roughly 28,000 light years, or slightly over half way to the galactic edge. One orbital period of our Solar System lasts between 225 and 250 million years.
Milky Way Galaxy	100,000 light-years across	Our home galaxy Galaxy A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a... , composed of 200 billion to 400 billion stars and filled with the interstellar medium Interstellar medium In astronomy, the interstellar medium is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, dust, and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space... .
Milky Way subgroup	1.64 million light-years across 0.5 megaparsecs	The Milky Way and those satellite galaxies gravitationally bound to it, such as the Sagittarius Dwarf Sagittarius Dwarf Elliptical Galaxy The Sagittarius Dwarf Elliptical Galaxy is an elliptical loop-shaped satellite galaxy of the Milky Way Galaxy. It consists of four globular clusters, the main cluster being discovered in 1994... , the Ursa Minor Dwarf Ursa Minor Dwarf The Ursa Minor Dwarf dwarf elliptical galaxy was discovered by A.G. Wilson of the Lowell Observatory in 1954. It is part of the Ursa Minor constellation, and a satellite galaxy to the Milky Way... and the Canis Major Dwarf. Cited distance is the orbital diameter of the Leo I Dwarf galaxy, the most distant galaxy in the Milky Way subgroup.
Local Group Local Group The Local Group is the group of galaxies that includes Earth's galaxy, the Milky Way. The group comprises more than 30 galaxies , with its gravitational center located somewhere between the Milky Way and the Andromeda Galaxy...	3 megaparsecs across	Group Galaxy groups and clusters Galaxy groups and clusters are the largest known gravitationally bound objects to have arisen thus far in the process of cosmic structure formation. They form the densest part of the large scale structure of the universe... of at least 47 galaxies. Dominated by Andromeda Andromeda Galaxy The Andromeda Galaxy is a spiral galaxy approximately 2.5 million light-years from Earth in the constellation Andromeda. It is also known as Messier 31, M31, or NGC 224, and is often referred to as the Great Andromeda Nebula in older texts. Andromeda is the nearest spiral galaxy to the... (the largest), The Milky Way and Triangulum Triangulum Galaxy The Triangulum Galaxy is a spiral galaxy approximately 3 million light years from Earth in the constellation Triangulum. It is catalogued as Messier 33 or NGC 598, and is sometimes informally referred to as the Pinwheel Galaxy, a nickname it shares with Messier 101... ; the remainder are small dwarf galaxies.
Virgo Supercluster Virgo Supercluster The Virgo Supercluster or Local Supercluster is the irregular supercluster that contains the Virgo Cluster in addition to the Local Group, which in turn contains the Milky Way and Andromeda galaxies. At least 100 galaxy groups and clusters are located within its diameter of 33 megaparsecs...	33 megaparsecs across	The supercluster Supercluster Superclusters are large groups of smaller galaxy groups and clusters and are among the largest known structures of the cosmos. They are so large that they are not gravitationally bound and, consequently, partake in the Hubble expansion.-Existence:... of which our Local Group is a part; comprises roughly 100 galaxy groups and clusters Galaxy groups and clusters Galaxy groups and clusters are the largest known gravitationally bound objects to have arisen thus far in the process of cosmic structure formation. They form the densest part of the large scale structure of the universe... .
Pisces-Cetus Supercluster Complex Pisces-Cetus Supercluster Complex The Pisces-Cetus Supercluster Complex is a complex of galaxy superclusters or galaxy filament that includes the Virgo Supercluster .-Discovery:...	300 megaparsecs across	The galaxy filament Galaxy filament In physical cosmology, galaxy filaments, also called supercluster complexes or great walls, are, so far, the largest known cosmic structures in the universe. They are massive, thread-like structures with a typical length of 50 to 80 megaparsecs h-1 that form the boundaries between large voids in... of which the Virgo Supercluster is a part.
Observable universe Observable universe In Big Bang cosmology, the observable universe consists of the galaxies and other matter that we can in principle observe from Earth in the present day, because light from those objects has had time to reach us since the beginning of the cosmological expansion...	28,000 megaparsecs across	The large-scale structure of the universe consists of more than 100 billion galaxies, arranged in millions of superclusters, galactic filaments, and voids Void (astronomy) In astronomy, voids are the empty spaces between filaments, the largest-scale structures in the Universe, that contain very few, or no, galaxies. They were first discovered in 1978 during a pioneering study by Stephen Gregory and Laird A. Thompson at the Kitt Peak National Observatory... , creating a foam-like superstructure.
Universe Universe The Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...	Minimum of 28,000 megaparsecs	Beyond the observable universe lies the unobservable regions where no light from those regions has reached the Earth yet. No information is available about the region, as light is the fastest travelling medium of information. However, since there is no reason to suppose different natural laws, the universe is likely to contain more galaxies in the same foam-like superstructure.
1 AU or astronomical unit Astronomical unit An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance.... 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. Existence is hypothetical. One light-year Light-year A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres... is the distance light travels in a year; equivalent to ~9.5 trillion km or 63,240 AU The Sun is not gravitationally tied to any larger structures within the Galaxy. These regions simply mark its current location in its orbit around the Galactic center. One megaparsec is equivalent to one million parsec Parsec The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres .... s or 3.26 million light-years. A parsec is the distance at which a star's parallax Parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines. The term is derived from the Greek παράλλαξις , meaning "alteration"... as viewed from Earth is equal to one second of arc.

See also