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Vesta (
minor-planet designation A formal minor planet designation is, in its final form, a number–name combination given to a minor planet (asteroid, centaur (minor planet), centaur, trans-Neptunian object and dwarf planet but not comet). Such designation always features a lea ...
: 4 Vesta) is one of the largest objects in the
asteroid belt The asteroid belt is a torus-shaped region in the Solar System The Solar SystemCapitalization Capitalization ( North American English) or capitalisation ( British English) is writing a word with its first letter as a capital lette ...

asteroid belt
, with a mean
diameter In geometry Geometry (from the grc, γεωμετρία; ''wikt:γῆ, geo-'' "earth", ''wikt:μέτρον, -metron'' "measurement") is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space ...

diameter
of . It was discovered by the German astronomer
Heinrich Wilhelm Matthias Olbers Heinrich Wilhelm Matthias Olbers (; ; 11 October 1758 – 2 March 1840) was a German physician A physician (American English), medical practitioner (English in the Commonwealth of Nations, Commonwealth English), medical doctor, or simply d ...

Heinrich Wilhelm Matthias Olbers
on 29 March 1807 and is named after Vesta, the virgin goddess of home and hearth from
Roman mythology Roman mythology is the body of myths of ancient Rome as represented in the Latin literature, literature and Roman art, visual arts of the Romans. One of a wide variety of genres of Roman folklore, ''Roman mythology'' may also refer to the moder ...
. Vesta is the second-largest asteroid, both by mass and by volume, after the
dwarf planet A dwarf planet is a small planetary-mass object that is in direct orbit of the Sun – something smaller than any of the eight classical planets, but still a world in its own right. The prototypical dwarf planet is Pluto. The interest of d ...
Ceres Ceres most commonly refers to: * Ceres (dwarf planet) Ceres (; minor-planet designation: 1 Ceres) is the smallest recognized dwarf planet, the closest dwarf planet to the Sun, and the List of notable asteroids, largest object in the main astero ...
. It constitutes an estimated 9% of the mass of the
asteroid belt The asteroid belt is a torus-shaped region in the Solar System The Solar SystemCapitalization Capitalization ( North American English) or capitalisation ( British English) is writing a word with its first letter as a capital lette ...

asteroid belt
. It is only slightly larger than
2 Pallas Pallas (minor-planet designation A formal minor-planet designation is, in its final form, a number–name combination given to a minor planet (asteroid, centaur (minor planet), centaur, trans-Neptunian object and dwarf planet but not comet) ...

2 Pallas
(about 5% by volume), but is 25% to 30% more massive. Vesta is the only known remaining rocky
protoplanet A protoplanet is a large planetary embryo that originated within a protoplanetary disc and has undergone internal melting to produce a differentiated interior. Protoplanets are thought to form out of kilometer-sized planetesimal 486958 Arrokoth, ...
(with a differentiated interior) of the kind that formed the
terrestrial planet A terrestrial planet, telluric planet, or rocky planet, is a planet that is composed primarily of silicate Rock (geology), rocks or metals. Within the Solar System, the terrestrial planets accepted by the IAU are the inner planets closest to the Su ...
s. Numerous fragments of Vesta were ejected by collisions one and two billion years ago that left two enormous craters occupying much of Vesta's southern hemisphere. Debris from these events has fallen to Earth as howardite–eucrite–diogenite (HED) meteorites, which have been a rich source of information about Vesta. Vesta is the
brightest asteroid The following is a collection of lists of exceptional asteroids in the Solar System. For the purposes of this article "asteroid" means minor planet up to the orbit of Neptune, which includes the likely dwarf planet Ceres (dwarf planet), Ceres, the ...
visible from Earth. It is regularly as bright as
magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...
5.1, at which times it is faintly visible to the naked eye. Its maximum distance from the
Sun The Sun is the star A star is an astronomical object consisting of a luminous spheroid of plasma (physics), plasma held together by its own gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many othe ...

Sun
is slightly greater than the minimum distance of Ceres from the Sun, though its orbit lies entirely within that of Ceres. NASA's ''Dawn'' spacecraft entered orbit around Vesta on 16 July 2011 for a one-year exploration and left the orbit of Vesta on 5 September 2012 en route to its final destination, Ceres. Researchers continue to examine data collected by ''Dawn'' for additional insights into the formation and history of Vesta.


History


Discovery

Heinrich Olbers discovered in 1802, the year after the discovery of
Ceres Ceres most commonly refers to: * Ceres (dwarf planet) Ceres (; minor-planet designation: 1 Ceres) is the smallest recognized dwarf planet, the closest dwarf planet to the Sun, and the List of notable asteroids, largest object in the main astero ...
. He proposed that the two objects were the remnants of a destroyed planet. He sent a letter with his proposal to the British astronomer
William Herschel Frederick William Herschel (; german: Friedrich Wilhelm Herschel; 15 November 1738 – 25 August 1822) was a German-born British astronomer and composer of music. He frequently collaborated with his younger sister and fellow astronomer Ca ...

William Herschel
, suggesting that a search near the locations where the orbits of Ceres and Pallas intersected might reveal more fragments. These orbital intersections were located in the
constellation A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived outline or pattern, typically representing an animal, mythological person or creature, or an inanimate object. The origins of the earliest ...

constellation
s of
Cetus Cetus () is a constellation, sometimes called 'the whale' in English. The Cetus (mythology), Cetus was a sea monster in Greek mythology which both Perseus and Heracles needed to slay. Cetus is in the region of the sky that contains other water- ...

Cetus
and
Virgo Virgo may refer to: * Virgo (surname) * Virgo (astrology) * Virgo (constellation), a constellation * Virgo Cluster, a cluster of galaxies in the constellation Virgo * Virgo Stellar Stream, remains of a dwarf galaxy * Virgo Supercluster, a galactic ...
. Olbers commenced his search in 1802, and on 29 March 1807 he discovered Vesta in the constellation Virgo—a coincidence, because Ceres, Pallas, and Vesta are not fragments of a larger body. Because the asteroid
Juno Juno commonly refers to: *Juno (mythology), the Roman goddess of marriage and queen of the gods *Juno (film), ''Juno'' (film), 2007 Juno may also refer to: Arts, entertainment and media Fictional characters *Juno, in the film ''Jenny, Juno'' *Jun ...
had been discovered in 1804, this made Vesta the fourth object to be identified in the region that is now known as the
asteroid belt The asteroid belt is a torus-shaped region in the Solar System The Solar SystemCapitalization Capitalization ( North American English) or capitalisation ( British English) is writing a word with its first letter as a capital lette ...

asteroid belt
. The discovery was announced in a letter addressed to German astronomer dated 31 March. Because Olbers already had credit for discovering a planet (Pallas; at the time, the asteroids were considered to be planets), he gave the honor of naming his new discovery to German mathematician
Carl Friedrich Gauss Johann Carl Friedrich Gauss (; german: Gauß ; la, Carolus Fridericus Gauss; 30 April 177723 February 1855) was a German mathematician This is a List of German mathematician A mathematician is someone who uses an extensive knowledge of m ...

Carl Friedrich Gauss
, whose orbital calculations had enabled astronomers to confirm the existence of Ceres, the first asteroid, and who had computed the orbit of the new planet in the remarkably short time of 10 hours. Gauss decided on the
Roman Roman or Romans most often refers to: *, the capital city of Italy *, Roman civilization from 8th century BC to 5th century AD *, the people of ancient Rome *', shortened to ''Romans'', a letter in the New Testament of the Christian Bible Roman ...
virgin goddess of home and hearth, Vesta.


Name

Vesta was the fourth asteroid to be discovered, hence the number 4 in its formal designation. The name ''Vesta'', or national variants thereof, is in international use with two exceptions:
Greece Greece ( el, Ελλάδα, Elláda, ), officially the Hellenic Republic, is a country located in Southeastern Europe Southeast Europe or Southeastern Europe () is a geographical subregion A subregion is a part of a larger region In geogr ...

Greece
and China. In
Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10.7 million as of ...
, the name adopted was the Hellenic equivalent of Vesta,
Hestia In the Ancient Greek religion Ancient Greek religion encompasses the collection of beliefs, rituals, and Greek mythology, mythology originating in ancient Greece in the form of both popular public religion and Cult (religious practice), cult p ...

Hestia
(); in English, that name is used for
46 Hestia Hestia (minor planet designation: 46 Hestia) is a large, dark asteroid belt, main-belt asteroid. It is also the primary body of the Hestia family, Hestia clump, a group of asteroids with similar orbits. Hestia was discovered by Norman Robert Pogso ...
(Greeks use the name "Hestia" for both, with the minor-planet numbers used for disambiguation). In
Chinese Chinese can refer to: * Something related to China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the List of countries and dependencies by population, world's most populous country, with a populat ...
, Vesta is called the 'hearth-god(dess) star', ', naming the asteroid for Vesta's role rather than literally transliterating her name into Chinese, as is done with other bodies discovered in modern times, including
Uranus Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus, who, according to Greek mythology Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and ...

Uranus
,
Neptune Neptune is the eighth and farthest-known Solar planet from the Sun. In the Solar System, it is the fourth-largest planet by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times the mass of Earth, slightly mor ...

Neptune
, and
Pluto Pluto (minor-planet designation A formal minor planet designation is, in its final form, a number–name combination given to a minor planet (asteroid, centaur (minor planet), centaur, trans-Neptunian object and dwarf planet but not comet ...

Pluto
. Upon its discovery, Vesta was, like Ceres, Pallas, and Juno before it, classified as a planet and given a
planetary symbol A planet symbol (or ''planetary symbol'') is a graphical symbol used in astrological symbol, astrology and astronomical symbol, astronomy to represent a classical planet (including the Sun and the Moon) or one of the modern planets. The symbols wer ...
. The symbol represented the altar of Vesta with its sacred fire and was designed by Gauss. In Gauss's conception, this was drawn in its modern form, it is After the discovery of Vesta, no further objects were discovered for 38 years, and the Solar System was thought to have eleven planets. However, in 1845, new asteroids started being discovered at a rapid pace, and by 1851 there were fifteen, each with its own symbol, in addition to the eight major planets (
Neptune Neptune is the eighth and farthest-known Solar planet from the Sun. In the Solar System, it is the fourth-largest planet by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times the mass of Earth, slightly mor ...

Neptune
had been discovered in 1846). It soon became clear that it would be impractical to continue inventing new planetary symbols indefinitely, and some of the existing ones proved difficult to draw quickly. That year, the problem was addressed by
Benjamin Apthorp Gould Benjamin Apthorp Gould (September 27, 1824 – November 26, 1896) was a pioneering American astronomer. He is noted for creating the ''Astronomical Journal'', discovering the Gould Belt, and for founding of the Argentine National Observatory and t ...
, who suggested numbering asteroids in their order of discovery, and placing this number in a disk (circle) as the generic symbol of an asteroid. Thus, the fourth asteroid, Vesta, acquired the generic symbol ④. This was soon coupled with the name into an official number–name designation, ''④ Vesta'', as the number of minor planets increased. By 1858, the circle had been simplified to parentheses, ''(4) Vesta'', which were easier to typeset. Other punctuation, such as ''4) Vesta'' and ''4, Vesta'', was also used, but had more or less completely died out by 1949. Today, either ''Vesta'', or, more commonly, ''4 Vesta'', is used.


Early measurements

Photometric observations of Vesta were made at the
Harvard College Observatory The Harvard College Observatory (HCO) is an institution managing a complex of buildings and multiple instruments used for astronomical research by the Harvard University Harvard University is a Private university, private Ivy League research ...
in 1880–1882 and at the in 1909. These and other observations allowed the rotation rate of Vesta to be determined by the 1950s. However, the early estimates of the rotation rate came into question because the
light curve Image:201 Penelope light curve.png, upright=1.25, Light curve of the asteroid 201 Penelope based on images taken on 6 October 2006 at Mount John University Observatory. Shows just over one full rotation period, rotation, which lasts 3.7474 hours. ...

light curve
included variations in both shape and
albedo Albedo (prounounced ; la, albedo, meaning 'whiteness') is the measure of the diffuse reflection of solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiat ...

albedo
. Early estimates of the diameter of Vesta ranged from in 1825, to . produced an estimated diameter of in 1879, which is close to the modern value for the mean diameter, but the subsequent estimates ranged from a low of up to a high of during the next century. The measured estimates were based on
photometryPhotometry can refer to: * Photometry (optics), the science of measurement of visible light in terms of its perceived brightness to human vision * Photometry (astronomy), the measurement of the flux or intensity of an astronomical object's electroma ...
. In 1989,
speckle interferometryImage:Zeta_bootis_short_exposure.png, Typical short-exposure image of a binary star (ζ Boötis) as seen through atmospheric turbulence. Each star should appear as a single point, but the atmosphere causes the images of the two stars to break up into ...
was used to measure a dimension that varied between during the rotational period. In 1991, an
occultation An occultation is an event that occurs when one object is hidden by another object that passes between it and the observer. The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks fro ...

occultation
of the star
SAO 93228 SAO or Sao may refer to: Places * Sao civilisation The Sao civilization (also called So) flourished in Central Africa Central Africa is a subregion of the African continent A continent is one of several large landmasses. Gener ...
by Vesta was observed from multiple locations in the eastern United States and Canada. Based on observations from 14 different sites, the best fit to the data was an elliptical profile with dimensions of about . ''
Dawn Dawn is the time that marks the beginning of twilight Twilight is the of the lower when the Sun is not directly visible because it is below the . Twilight is produced by in the upper atmosphere, illuminating the lower atmosphere so ...
'' confirmed this measurement. Vesta became the first asteroid to have its mass determined. Every 18 years, the asteroid
197 Arete Arete (minor planet designation A formal minor planet designation is, in its final form, a number–name combination given to a minor planet A minor planet is an astronomical object in direct orbit In physics, an orbit is the gravita ...
approaches within of Vesta. In 1966, based upon observations of Vesta's
gravitational perturbation In astronomy Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a natural science that studies astronomical object, celestial objects and celestial event, phenomena. It uses mat ...

gravitational perturbation
s of Arete, Hans G. Hertz estimated the mass of Vesta at (
solar mass The solar mass () is a standard unit of mass in astronomy Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a natural science that studies astronomical object, celestial obje ...
es). More refined estimates followed, and in 2001 the perturbations of
17 Thetis Thetis, minor planet designation 17 Thetis, is a stony asteroid from the inner regions of the asteroid belt, approximately 90 kilometers in diameter. It was discovered on 17 April 1852, by German astronomer Robert Luther at Bilk Observatory in D ...
were used to calculate the mass of Vesta to be . ''Dawn'' determined it to be .


Orbit

Vesta orbits the Sun between Mars and Jupiter, within the
asteroid belt The asteroid belt is a torus-shaped region in the Solar System The Solar SystemCapitalization Capitalization ( North American English) or capitalisation ( British English) is writing a word with its first letter as a capital lette ...

asteroid belt
, with a period of 3.6 Earth years, specifically in the inner asteroid belt, interior to the
Kirkwood gap upright=1.35, Relation between Jovian orbital resonance and the distance from the Sun in Kirkwood gaps A Kirkwood gap is a gap or dip in the distribution of the semi-major axis, semi-major axes (or equivalently of the orbital periods) of the orbit ...
at 2.50 AU. Its orbit is moderately inclined (''i'' = 7.1°, compared to 7° for
Mercury Mercury usually refers to: * Mercury (planet) Mercury is the smallest planet in the Solar System and the closest to the Sun. Its orbit around the Sun takes 87.97 Earth days, the shortest of all the Sun's planets. It is named after the Roman g ...

Mercury
and 17° for
Pluto Pluto (minor-planet designation A formal minor planet designation is, in its final form, a number–name combination given to a minor planet (asteroid, centaur (minor planet), centaur, trans-Neptunian object and dwarf planet but not comet ...

Pluto
) and moderately eccentric (''e'' = 0.09, about the same as for Mars). True
orbital resonance . Conjunctions ''Conjunctions'' is a biannual American literature, American literary journal based at Bard College. It was founded in 1981 and is currently edited by Bradford Morrow. Morrow received the PEN/Nora Magid Award for Magazine Editing ...
s between asteroids are considered unlikely; due to their small masses relative to their large separations, such relationships should be very rare. Nevertheless, Vesta is able to capture other asteroids into temporary 1:1 resonant orbital relationships (for periods up to 2 million years or more); about forty such objects have been identified. Decameter-sized objects detected in the vicinity of Vesta by ''Dawn'' may be such
quasi-satellite A quasi-satellite is an object in a specific type of co-orbital configuration (1:1 orbital resonance . Conjunctions are highlighted by brief color changes. There are two Io-Europa conjunctions (green) and three Io-Ganymede conjunctions (grey) f ...
s rather than proper satellites.


Rotation

Vesta's rotation is relatively fast for an asteroid (5.342 h) and prograde, with the north pole pointing in the direction of
right ascension Right ascension (abbreviated RA; symbol ) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the equinox (celestial coordinates), March equinox to the (hour circle of the) point in question ...

right ascension
20 h 32 min,
declination In astronomy Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a natural science that studies astronomical object, celestial objects and celestial event, phenomena. It uses math ...
+48° (in the constellation Cygnus) with an uncertainty of about 10°. This gives an
axial tilt In , axial tilt, also known as obliquity, is the angle between an object's and its al axis, or, equivalently, the angle between its ial plane and . It differs from . At an obliquity of 0 degrees, the two axes point in the same direction; i.e., ...
of 29°.


Coordinate systems

There are two longitudinal coordinate systems in use for Vesta, with
prime meridian #REDIRECT Prime meridian#REDIRECT Prime meridian A prime meridian is the meridian (geography), meridian (a line of longitude) in a geographic coordinate system at which longitude is defined to be 0°. Together, a prime meridian and its anti-meri ...

prime meridian
s separated by 150°. The
IAU The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a Non-governmental organization, nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting ...

IAU
established a coordinate system in 1997 based on ''Hubble'' photos, with the prime meridian running through the center of , a dark feature 200 km across. When ''Dawn'' arrived at Vesta, mission scientists found that the location of the pole assumed by the IAU was off by 10°, so that the IAU coordinate system drifted across the surface of Vesta at 0.06° per year, and also that Olbers Regio was not discernible from up close, and so was not adequate to define the prime meridian with the precision they needed. They corrected the pole, but also established a new prime meridian 4° from the center of
ClaudiaClaudia may refer to: People Ancient Romans *Any woman from the Roman Claudia gens *Claudia (vestal), a Vestal Virgin who protected her father Appius Claudius Pulcher in 143 BC *Claudia Augusta (63–63 AD), infant daughter of Nero by his second w ...
, a sharply defined crater 700 meters across, which they say results in a more logical set of mapping quadrangles. All NASA publications, including images and maps of Vesta, use the Claudian meridian, which is unacceptable to the IAU. The IAU Working Group on Cartographic Coordinates and Rotational Elements recommended a coordinate system, correcting the pole but rotating the Claudian longitude by 150° to coincide with Olbers Regio. It was accepted by the IAU, though it disrupts the maps prepared by the ''Dawn'' team, which had been positioned so they would not bisect any major surface features.


Physical characteristics

Vesta is the second-most-massive body in the
asteroid belt The asteroid belt is a torus-shaped region in the Solar System The Solar SystemCapitalization Capitalization ( North American English) or capitalisation ( British English) is writing a word with its first letter as a capital lette ...

asteroid belt
, though only 28% as massive as Ceres. Vesta's density is lower than those of the four
terrestrial planet A terrestrial planet, telluric planet, or rocky planet, is a planet that is composed primarily of silicate Rock (geology), rocks or metals. Within the Solar System, the terrestrial planets accepted by the IAU are the inner planets closest to the Su ...
s, but higher than that of most asteroids and all of the moons in the Solar System except Io. Vesta's surface area is about the same as that of
Pakistan Pakistan, . Pronounced variably in English as , , , and . officially the Islamic Republic of Pakistan, is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a popul ...

Pakistan
, or
Texas Texas (, ; Spanish Spanish may refer to: * Items from or related to Spain: **Spaniards, a nation and ethnic group indigenous to Spain **Spanish language **Spanish cuisine Other places * Spanish, Ontario, Canada * Spanish River (disambigu ...

Texas
and
North Carolina North Carolina () is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspaper), a daily news ...

North Carolina
combined (about 800,000 square kilometers). It has a differentiated interior. Vesta is only slightly larger () than
2 Pallas Pallas (minor-planet designation A formal minor-planet designation is, in its final form, a number–name combination given to a minor planet (asteroid, centaur (minor planet), centaur, trans-Neptunian object and dwarf planet but not comet) ...

2 Pallas
() in volume, but is about 25% more massive. Vesta's shape is close to a gravitationally relaxed
oblate spheroid A spheroid, also known as an ellipsoid of revolution or rotational ellipsoid, is a quadric In mathematics, a quadric or quadric surface (quadric hypersurface in higher dimension thumb , 236px , The first four spatial dimensions, repres ...
, but the large concavity and protrusion at the southern pole (see ' Surface features' below) combined with a mass less than precluded Vesta from automatically being considered a
dwarf planet A dwarf planet is a small planetary-mass object that is in direct orbit of the Sun – something smaller than any of the eight classical planets, but still a world in its own right. The prototypical dwarf planet is Pluto. The interest of d ...
under . A 2012 analysis of Vesta's shape and gravity field using data gathered by the ''Dawn'' spacecraft has shown that Vesta is currently not in
hydrostatic equilibrium In fluid mechanics Fluid mechanics is the branch of physics concerned with the mechanics Mechanics (Ancient Greek, Greek: ) is the area of physics concerned with the motions of physical objects, more specifically the relationships among fo ...

hydrostatic equilibrium
. Temperatures on the surface have been estimated to lie between about −20 °C with the
Sun The Sun is the star A star is an astronomical object consisting of a luminous spheroid of plasma (physics), plasma held together by its own gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many othe ...

Sun
overhead, dropping to about −190 °C at the winter pole. Typical daytime and nighttime temperatures are −60 °C and −130 °C respectively. This estimate is for 6 May 1996, very close to
perihelion upright=1.15, The two-body system of interacting primary body (yellow); both are in elliptic orbits around their center of mass">common center of mass (or barycenter), (red +). ∗Periapsis and apoapsis as distances: The smallest and largest ...

perihelion
, although details vary somewhat with the seasons.


Surface features

Prior to the arrival of the ''Dawn'' spacecraft, some Vestan surface features had already been resolved using the
Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope A space telescope or space observatory is a telescope in outer space used to observe astronomical objects. Suggested by Lyman Spitzer in 1946, the first ...

Hubble Space Telescope
and ground-based telescopes (e.g. the
Keck Observatory The W. M. Keck Observatory is a two-telescope astronomical observatory at an elevation of 4,145 meters (13,600 ft) near the summit of Mauna Kea in the U.S. state of Hawaii Hawaii ( ; haw, Hawaii or ) is a U.S. state in the Weste ...
). The arrival of ''Dawn'' in July 2011 revealed the complex surface of Vesta in detail.


Rheasilvia and Veneneia craters

The most prominent of these surface features are two enormous craters, the -wide Rheasilvia crater, centered near the south pole, and the wide Veneneia crater. The Rheasilvia crater is younger and overlies the Veneneia crater. The ''Dawn'' science team named the younger, more prominent crater
Rheasilvia Rheasilvia is the most prominent surface feature on the asteroid An asteroid is a minor planet of the Solar System#Inner solar system, inner Solar System. Historically, these terms have been applied to any astronomical object orbiting the ...
, after the mother of Romulus and Remus and a mythical
vestal virgin In ancient Rome, the Vestals or Vestal Virgins (Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Lati ...
. Its width is 95% of the mean diameter of Vesta. The crater is about deep. A central peak rises above the lowest measured part of the crater floor and the highest measured part of the crater rim is above the crater floor low point. It is estimated that the impact responsible excavated about 1% of the volume of Vesta, and it is likely that the
Vesta familyThe Vesta family (adj. ''Vestian''; ) is a family In human society, family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of familie ...

Vesta family
and
V-type asteroidA V-type asteroid or Vestoid is an asteroid An asteroid is a minor planet of the Solar System#Inner solar system, inner Solar System. Historically, these terms have been applied to any astronomical object orbiting the Sun that did not resolve in ...
s are the products of this collision. If this is the case, then the fact that fragments have survived bombardment until the present indicates that the crater is at most only about 1 billion years old. It would also be the site of origin of the
HED meteorite HED meteorites are a clan (subgroup) of achondrite An achondrite is a stony meteorite that does not contain chondrules. It consists of material similar to terrestrial basalts or plutonic rocks and has been differentiated and reprocessed to a lesser ...
s. All the known V-type asteroids taken together account for only about 6% of the ejected volume, with the rest presumably either in small fragments, ejected by approaching the 3:1 
Kirkwood gap upright=1.35, Relation between Jovian orbital resonance and the distance from the Sun in Kirkwood gaps A Kirkwood gap is a gap or dip in the distribution of the semi-major axis, semi-major axes (or equivalently of the orbital periods) of the orbit ...
, or perturbed away by the
Yarkovsky effectImage:YarkovskyEffect.svg, 300px, Yarkovsky effect:1. Radiation from asteroid's surface 2. Prograde rotating asteroid 2.1 Location with "Afternoon" 3. Asteroid's orbit 4. Radiation from Sun The Yarkovsky effect is a Force (physics), force acting on ...
or
radiation pressure Radiation pressure is the mechanical pressure exerted upon any surface due to the exchange of momentum between the object and the electromagnetic field. This includes the momentum of light or electromagnetic radiation of any wavelength which is Ab ...

radiation pressure
.
Spectroscopic Spectroscopy is the study of the interaction between matter and Electromagnetism, electromagnetic radiation as a function of the wavelength or frequency of the radiation. In simpler terms, spectroscopy is the precise study of color as generalize ...

Spectroscopic
analyses of the Hubble images have shown that this crater has penetrated deep through several distinct layers of the crust, and possibly into the
mantle Mantle may refer to: *Mantle (geology) A mantle is a layer inside a planetary body A planet is an astronomical body Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a n ...
, as indicated by spectral signatures of
olivine The mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. R ...

olivine
. The large peak at the center of Rheasilvia is high and wide, and is possibly a result of a planetary-scale impact.


Other craters

Several old, degraded craters rival Rheasilvia and Veneneia in size, though none are quite so large. They include Feralia Planitia, shown at right, which is across. More-recent, sharper craters range up to Varronilla and Postumia.


"Snowman craters"

The "snowman craters" is an informal name given to a group of three adjacent craters in Vesta's northern hemisphere. Their official names from largest to smallest (west to east) are Marcia, Calpurnia, and Minucia. Marcia is the youngest and cross-cuts Calpurnia. Minucia is the oldest.


Troughs

The majority of the equatorial region of Vesta is sculpted by a series of parallel troughs. The largest is named Divalia Fossa (10–20 km wide, 465 km long). Despite the fact that Vesta is a one-seventh the size of the Moon, Divalia Fossa dwarfs the
Grand Canyon The Grand Canyon (, yuf-x-yav, Wi:kaʼi:la, , ) is a steep-sided canyon A canyon (; archaic British English spelling: ''cañon'') or gorge is a deep cleft between escarpments or cliffs resulting from weathering and the erosion, erosive ...

Grand Canyon
. A second series, inclined to the equator, is found further north. The largest of the northern troughs is named
Saturnalia Fossa Saturnalia Fossa is the largest of the series of parallel Veneneian troughs in the northern hemisphere of the giant asteroid 4 Vesta Vesta ( minor-planet designation: 4 Vesta) is one of the largest objects in the asteroid belt The aste ...
(≈ 40 km wide, > 370 km long). These troughs are thought to be large-scale
graben In geology Geology (from the γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is a branch of concerned with both the liquid and , the of which it is composed, and the processes by which they change over ti ...

graben
resulting from the impacts that created Rheasilvia and Veneneia craters, respectively. They are some of the longest chasms in the Solar System, nearly as long as on Tethys. The troughs may be graben that formed after another asteroid collided with Vesta, a process that can happen only in a body that, like Vesta, is differentiated. Vesta's differentiation is one of the reasons why scientists consider it a protoplanet.


Surface composition

Compositional information from the visible and infrared spectrometer (VIR), gamma-ray and neutron detector (GRaND), and framing camera (FC), all indicate that the majority of the surface composition of Vesta is consistent with the composition of the howardite, eucrite, and diogenite meteorites. The Rheasilvia region is richest in diogenite, consistent with the Rheasilvia-forming impact excavating material from deeper within Vesta. The presence of olivine within the Rheasilvia region would also be consistent with excavation of mantle material. However, olivine has only been detected in localized regions of the northern hemisphere, not within Rheasilvia. The origin of this olivine is currently unknown.


Features associated with volatiles

Pitted terrain has been observed in four craters on Vesta: Marcia, Cornelia, Numisia and Licinia. The formation of the pitted terrain is proposed to be degassing of impact-heated volatile-bearing material. Along with the pitted terrain, curvilinear gullies are found in Marcia and Cornelia craters. The curvilinear gullies end in lobate deposits, which are sometimes covered by pitted terrain, and are proposed to form by the transient flow of liquid water after buried deposits of ice were melted by the heat of the impacts. Hydrated materials have also been detected, many of which are associated with areas of dark material. Consequently, dark material is thought to be largely composed of carbonaceous chondrite, which was deposited on the surface by impacts. Carbonaceous chondrites are comparatively rich in mineralogically bound OH.


Geology

There is a large collection of potential samples from Vesta accessible to scientists, in the form of over 1200 
HED meteorite HED meteorites are a clan (subgroup) of achondrite An achondrite is a stony meteorite that does not contain chondrules. It consists of material similar to terrestrial basalts or plutonic rocks and has been differentiated and reprocessed to a lesser ...
s (Vestan
achondrite An achondrite is a stony meteorite A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet ...
s), giving insight into Vesta's geologic history and structure.
NASA Infrared Telescope Facility The NASA Infrared Telescope Facility (NASA IRTF) is a telescope A telescope is an optical instrument using lenses, curved mirrors, or a combination of both to observe distant objects, or various devices used to observe distant objects by t ...

NASA Infrared Telescope Facility
(NASA IRTF) studies of asteroid suggest that it originated from deeper within Vesta than the HED meteorites Vesta is thought to consist of a metallic iron–nickel
core Core or cores may refer to: Science and technology * Core (anatomy) In common parlance, the core of the body is broadly considered to be the torso. Functional movements are highly dependent on this part of the body, and lack of core muscular dev ...
214–226 km in diameter, an overlying rocky
olivine The mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. R ...

olivine
mantle Mantle may refer to: *Mantle (geology) A mantle is a layer inside a planetary body A planet is an astronomical body Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a n ...
, with a surface crust. From the first appearance of calcium–aluminium-rich inclusions (the first solid matter in the
Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

Solar System
, forming about 4.567 billion years ago), a likely time line is as follows: : Vesta is the only known intact asteroid that has been resurfaced in this manner. Because of this, some scientists refer to Vesta as a protoplanet. However, the presence of
iron meteorite Iron meteorites, also known as siderite :''Siderite is also the name of a type of iron meteorite Iron meteorites, also known as siderites, or ferrous meteorites, are a type of meteorites that consist overwhelmingly of an iron–nickel alloy known ...
s and achondritic meteorite classes without identified parent bodies indicates that there once were other differentiated
planetesimal 486958 Arrokoth, the first pristine planetesimal visited by a spacecraft. Planetesimals are solid objects thought to exist in protoplanetary disks and debris disks. Per the Chamberlin–Moulton planetesimal hypothesis, they are believed to fo ...
s with
igneous Igneous rock (derived from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the p ...
histories, which have since been shattered by impacts. : On the basis of the sizes of
V-type asteroidA V-type asteroid or Vestoid is an asteroid An asteroid is a minor planet of the Solar System#Inner solar system, inner Solar System. Historically, these terms have been applied to any astronomical object orbiting the Sun that did not resolve in ...
s (thought to be pieces of Vesta's crust ejected during large impacts), and the depth of Rheasilvia crater (see below), the crust is thought to be roughly thick. Findings from the ''Dawn'' spacecraft have found evidence that the troughs that wrap around Vesta could be graben formed by impact-induced faulting (see Troughs section above), meaning that Vesta has more complex geology than other asteroids. Vesta's differentiated interior implies that it was in hydrostatic equilibrium and thus a dwarf planet in the past, but it is not today. The impacts that created the Rheasilvia and Veneneia craters occurred when Vesta was no longer warm and plastic enough to return to an equilibrium shape, distorting its once rounded shape and prohibiting it from being classified as a dwarf planet today.


Regolith

Vesta's surface is covered by
regolith Regolith () is a blanket of unconsolidated, loose, Homogeneity and heterogeneity, heterogeneous superficial deposits covering solid Rock (geology), rock. It includes dust, broken rocks, and other related materials and is present on Earth, the Moo ...

regolith
distinct from that found on the
Moon The Moon is Earth's only natural satellite. At about one-quarter the diameter of Earth (comparable to the width of Australia (continent), Australia), it is the largest natural satellite in the Solar System relative to the size of its plane ...

Moon
or asteroids such as Itokawa. This is because
space weathering Space weathering is the type of weathering that occurs to any object exposed to the harsh Space environment, environment of outer space. Bodies without atmospheres (including the Moon, Mercury (planet), Mercury, the asteroids, comets, and most of t ...
acts differently. Vesta's surface shows no significant trace of nanophase iron because the
impact Impact may refer to: * Impact (mechanics), a high force or shock (mechanics) over a short time period * Impact, Texas, a town in Taylor County, Texas, US Science and technology * Impact crater, a meteor crater caused by an impact event * Impact e ...

impact
speeds on Vesta are too low to make rock melting and vaporization an appreciable process. Instead, regolith evolution is dominated by and subsequent mixing of bright and dark components. The dark component is probably due to the infall of
carbon Carbon (from la, carbo "coal") is a with the C and 6. It is lic and —making four s available to form s. It belongs to group 14 of the periodic table. Carbon makes up only about 0.025 percent of Earth's crust. Three occur naturally, ...

carbon
aceous material, whereas the bright component is the original Vesta basaltic soil.


Fragments

Some
small Solar System bodies A small Solar System body (SSSB) is an object in the Solar System that is neither a planet, a dwarf planet, nor a natural satellite. The term was first IAU definition of planet, defined in 2006 by the International Astronomical Union (IAU) as foll ...
are suspected to be fragments of Vesta caused by impacts. The asteroids and
HED meteorite HED meteorites are a clan (subgroup) of achondrite An achondrite is a stony meteorite that does not contain chondrules. It consists of material similar to terrestrial basalts or plutonic rocks and has been differentiated and reprocessed to a lesser ...
s are examples. The
V-type asteroidA V-type asteroid or Vestoid is an asteroid An asteroid is a minor planet of the Solar System#Inner solar system, inner Solar System. Historically, these terms have been applied to any astronomical object orbiting the Sun that did not resolve in ...
1929 Kollaa 1929 Kollaa, provisional designation , is a stony Vestian asteroid from the inner regions of the asteroid belt, approximately 7 kilometers in diameter. It was discovered by Finnish astronomer Yrjö Väisälä at Iso-Heikkilä Observatory, Turku Obs ...
has been determined to have a composition akin to cumulate
eucrite Eucrites are achondrite, achondritic stony meteorites, many of which originate from the surface of the asteroid 4 Vesta and as such are part of the HED meteorite clan. They are the most common achondrite group with well over 100 distinct finds at ...
meteorites, indicating its origin deep within Vesta's crust. Vesta is currently one of only six identified
Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

Solar System
bodies of which we have physical samples, coming from a number of meteorites suspected to be Vestan fragments. It is estimated that 1 out of 16 meteorites originated from Vesta. The other identified Solar System samples are from Earth itself, meteorites from Mars, meteorites from the Moon, and samples returned from the
Moon The Moon is Earth's only natural satellite. At about one-quarter the diameter of Earth (comparable to the width of Australia (continent), Australia), it is the largest natural satellite in the Solar System relative to the size of its plane ...

Moon
, the comet
Wild 2 Comet 81P/Wild, also known as Wild 2 (pronounced "vilt two") ( ), is a comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produ ...

Wild 2
, and the asteroid
25143 Itokawa 25143 Itokawa (provisional designation ) is a sub-kilometer near-Earth object of the Apollo asteroid, Apollo group and a potentially hazardous asteroid. It was discovered by the LINEAR program in 1998 and later named after Japanese rocket engine ...
.


Exploration

In 1981, a proposal for an asteroid mission was submitted to the
European Space Agency , owner = , headquarters = Paris, Île-de-France, France , coordinates = , spaceport = Guiana Space Centre , seal = File:ESA emblem seal.png , seal_size = 130px , image = ESA Headquarters in Paris, France, 2 ...

European Space Agency
(ESA). Named the Asteroidal Gravity Optical and Radar Analysis (AGORA), this
spacecraft A spacecraft is a vehicle or machine designed to fly in outer space. A type of artificial satellite alt=, A full-size model of the Earth observation satellite ERS 2 ">ERS_2.html" ;"title="Earth observation satellite ERS 2">Earth obse ...

spacecraft
was to launch some time in 1990–1994 and perform two flybys of large asteroids. The preferred target for this mission was Vesta. AGORA would reach the asteroid belt either by a
gravitational slingshot In orbital mechanics and aerospace engineering Aerospace engineering is the primary field of engineering Engineering is the use of scientific method, scientific principles to design and build machines, structures, and other items, in ...

gravitational slingshot
trajectory past Mars or by means of a small
ion engine An ion thruster, ion drive, or ion engine is a form of electrically powered spacecraft propulsion, electric propulsion used for spacecraft propulsion. It creates thrust by accelerating ions using electricity. An ion thruster ionizes a neutr ...

ion engine
. However, the proposal was refused by the ESA. A joint
NASA The National Aeronautics and Space Administration (NASA; ) is an independent agency A regulatory agency or regulatory authority, is a Public benefit corporation Public-benefit corporation is a term that has different meanings in differen ...

NASA
–ESA asteroid mission was then drawn up for a Multiple Asteroid Orbiter with Solar Electric Propulsion (MAOSEP), with one of the mission profiles including an orbit of Vesta. NASA indicated they were not interested in an asteroid mission. Instead, the ESA set up a technological study of a spacecraft with an ion drive. Other missions to the asteroid belt were proposed in the 1980s by France, Germany, Italy and the United States, but none were approved. Exploration of Vesta by fly-by and impacting penetrator was the second main target of the first plan of the multi-aimed Soviet Vesta mission, developed in cooperation with European countries for realisation in 1991–1994 but canceled due to the
dissolution of the Soviet Union The dissolution of the Soviet Union, also negatively connoted as rus, Разва́л Сове́тского Сою́за, r=Razvál Sovétskovo Sojúza, ''Ruining of the Soviet Union''. (1988–1991) was the process of internal political, ...
. In the early 1990s, NASA initiated the
Discovery Program Asteroid 433 Eros, Eros regolith, as viewed by Discovery's NEAR Shoemaker mission The Discovery Program is a series of Solar System exploration missions funded by the US National Aeronautics and Space Administration (NASA) through its Planetar ...
, which was intended to be a series of low-cost scientific missions. In 1996, the program's study team recommended a mission to explore the asteroid belt using a spacecraft with an ion engine as a high priority. Funding for this program remained problematic for several years, but by 2004 the ''
Dawn Dawn is the time that marks the beginning of twilight Twilight is the of the lower when the Sun is not directly visible because it is below the . Twilight is produced by in the upper atmosphere, illuminating the lower atmosphere so ...
'' vehicle had passed its critical design review and construction proceeded. It launched on 27 September 2007 as the first space mission to Vesta. On 3 May 2011, ''Dawn'' acquired its first targeting image 1.2 million kilometers from Vesta. On 16 July 2011, NASA confirmed that it received telemetry from ''Dawn'' indicating that the spacecraft successfully entered Vesta's orbit. It was scheduled to orbit Vesta for one year, until July 2012. ''Dawn'' arrival coincided with late summer in the southern hemisphere of Vesta, with the large crater at Vesta's south pole (
Rheasilvia Rheasilvia is the most prominent surface feature on the asteroid An asteroid is a minor planet of the Solar System#Inner solar system, inner Solar System. Historically, these terms have been applied to any astronomical object orbiting the ...
) in sunlight. Because a season on Vesta lasts eleven months, the northern hemisphere, including anticipated compression fractures opposite the crater, would become visible to ''Dawn'' cameras before it left orbit. ''Dawn'' left orbit around Vesta on 4 September 2012 to travel to
Ceres Ceres most commonly refers to: * Ceres (dwarf planet) Ceres (; minor-planet designation: 1 Ceres) is the smallest recognized dwarf planet, the closest dwarf planet to the Sun, and the List of notable asteroids, largest object in the main astero ...
. NASA/DLR released imagery and summary information from a survey orbit, two high-altitude orbits (60–70 m/pixel) and a low-altitude mapping orbit (20 m/pixel), including digital terrain models, videos and atlases. Scientists also used ''Dawn'' to calculate Vesta's precise mass and gravity field. The subsequent determination of the J2 component yielded a core diameter estimate of about 220 km assuming a crustal density similar to that of the HED. ''Dawn'' data can be accessed by the public at the
UCLA The University of California, Los Angeles (UCLA) is a public In public relations Public relations (PR) is the practice of managing and disseminating information from an individual or an organization An organization, or organ ...
website.


Observations from Earth orbit

File:Vesta spectral map HST1994.jpg,
Albedo Albedo (prounounced ; la, albedo, meaning 'whiteness') is the measure of the diffuse reflection of solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiat ...

Albedo
and spectral maps of 4 Vesta, as determined from Hubble Space Telescope images from November 1994 File:Vesta elevation map HST1996.jpg, Elevation map of 4 Vesta, as determined from Hubble Space Telescope images of May 1996 File:Vesta-Elevation.jpg, Elevation diagram of 4 Vesta (as determined from
Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope A space telescope or space observatory is a telescope in outer space used to observe astronomical objects. Suggested by Lyman Spitzer in 1946, the first ...

Hubble Space Telescope
images of May 1996) viewed from the south-east, showing
Rheasilvia Rheasilvia is the most prominent surface feature on the asteroid An asteroid is a minor planet of the Solar System#Inner solar system, inner Solar System. Historically, these terms have been applied to any astronomical object orbiting the ...
crater at the south pole and Feralia Planitia near the equator File:Vesta-HST-Color.jpg, Vesta seen by the
Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope A space telescope or space observatory is a telescope in outer space used to observe astronomical objects. Suggested by Lyman Spitzer in 1946, the first ...

Hubble Space Telescope
in May 2007


Observations from ''Dawn''

Vesta comes into view as the ''Dawn'' spacecraft approaches and enters orbit: File:Vesta 20110701 cropped.jpg, Vesta from 100,000 km
(1 July 2011) File:Dawn-image-070911.jpg, Vesta from 41,000 km
(9 July 2011) File:Vesta from Dawn, July 17.jpg, In orbit at 16,000 km
(17 July 2011) File:Vesta 4.jpg, In orbit from 10,500 km
(18 July 2011) File:Vesta darkside.jpg, The northern hemisphere from 5,200 km
(23 July 2011) File:Vesta Full-Frame.jpg, In orbit from 5,200 km
(24 July 2011) File:Vesta 20110731.jpg, In orbit from 3,700 km
(31 July 2011) File:Vesta Rotation.gif, Full rotation
(1 August 2011) File:Vesta Cratered terrain with hills and ridges.jpg, Cratered terrain with hills and ridges
(6 August 2011) File:Vesta densely cratered terrain near terminator.jpg, Densely cratered terrain near terminator
(6 August 2011) File:Vesta Craters in various states of degradation.jpg, Vestan craters in various states of degradation, with troughs at bottom
(6 August 2011) File:Central Mound at the South Pole Asteroid Vesta Hillshade.png, Hill shaded central mound at the south pole of Vesta
(2 February 2015)


True-color images

Vesta in natural color.jpg Vesta-SouthPole.png Vesta 5755-728.png Detailed images retrieved during the high-altitude (60–70 m/pixel) and low-altitude (~20 m/pixel) mapping orbits are available on th
Dawn Mission website of JPL/NASA


Visibility

Its size and unusually bright surface make Vesta the brightest asteroid, and it is occasionally visible to the
naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception Visual perception is the ability to interpret the surrounding environment (biophysical), environment through photopic vision (daytime vision ...
from dark skies (without
light pollution Light pollution is the presence of unwanted, inappropriate, or excessive artificial lighting Lighting or illumination is the deliberate use of light Light or visible light is electromagnetic radiation within the portion of the elect ...

light pollution
). In May and June 2007, Vesta reached a peak
magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

magnitude
of +5.4, the brightest since 1989. At that time,
opposition Opposition may refer to: Arts and media * Opposition (Altars EP), ''Opposition'' (Altars EP), 2011 EP by Christian metalcore band Altars * The Opposition (band), a London post-punk band * ''The Opposition with Jordan Klepper'', a late-night tele ...

opposition
and
perihelion upright=1.15, The two-body system of interacting primary body (yellow); both are in elliptic orbits around their center of mass">common center of mass (or barycenter), (red +). ∗Periapsis and apoapsis as distances: The smallest and largest ...

perihelion
were only a few weeks apart. It was brighter still at its 22 June 2018 opposition, reaching a magnitude of +5.3. Less favorable oppositions during late autumn 2008 in the
Northern Hemisphere The Northern Hemisphere is the half of Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. The remain ...

Northern Hemisphere
still had Vesta at a magnitude of from +6.5 to +7.3. Even when in
conjunction Conjunction may refer to: * Conjunction (astronomy), in which two astronomical bodies appear close together in the sky * Conjunction (astrology), astrological aspect in horoscopic astrology * Conjunction (grammar), a part of speech * Logical conjun ...
with the Sun, Vesta will have a magnitude around +8.5; thus from a pollution-free sky it can be observed with
binoculars Binoculars or field glasses are two telescope A telescope is an optical instrument An optical instrument (or "optic" for short) is a device that processes light waves (or photon The photon (Greek: φῶς, phōs, light) is a type of ele ...
even at elongations much smaller than near opposition.


2010–2011

In 2010, Vesta reached opposition in the
constellation A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived outline or pattern, typically representing an animal, mythological person or creature, or an inanimate object. The origins of the earliest ...

constellation
of
Leo Leo is the Latin word for "lion". Leo or LEO may refer to: * Leo (astrology), an astrological sign * Leo (constellation), a constellation in the sky Arts and entertainment * Leo (band), a Missouri-based rock band that was founded in Clevelan ...
on the night of 17–18 February, at about magnitude 6.1, a brightness that makes it visible in binocular range but generally not for the
naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception Visual perception is the ability to interpret the surrounding environment (biophysical), environment through photopic vision (daytime vision ...
. Under perfect dark sky conditions where all light pollution is absent it might be visible to an experienced observer without the use of a telescope or binoculars. Vesta came to opposition again on 5 August 2011, in the constellation of
Capricornus Capricornus is one of the constellations of the zodiac. Its name is Latin for "horned goat" or "goat Horn (anatomy), horn" or "having horns like a goat's", and it is commonly represented in the form of a sea goat: a mythical creature that is hal ...

Capricornus
at about magnitude 5.6.


2012–2013

Vesta was at opposition again on 9 December 2012. According to ''
Sky and Telescope ''Sky & Telescope'' (''S&T'') is a monthly American magazine covering all aspects of amateur astronomy Image:Astronomy Amateur 3 V2.jpg, 250px, Amateur astronomers watch the night sky during the Perseids, Perseid meteor shower. Amateur astronomy ...
'' magazine, this year Vesta came within about 6 degrees of 1 Ceres during the winter of 2012 and spring 2013. Vesta orbits the Sun in 3.63 years and Ceres in 4.6 years, so every 17.4 years Vesta overtakes Ceres (the previous overtaking was in April 1996). On 1 December 2012, Vesta had a magnitude of 6.6, but it had decreased to 8.4 by 1 May 2013.


2014

Ceres and Vesta came within one degree of each other in the night sky in July 2014.


See also

* 3103 Eger * 3551 Verenia *
3908 Nyx 3908 Nyx is an Amor and Mars-crosser asteroid A Mars-crossing asteroid (MCA, also Mars-crosser, MC) is an asteroid whose orbit crosses that of Mars. The known numbered Mars-crossers are listed here. They include the two numbered Mars trojans ...
* 4055 Magellan *
Asteroids in fiction Asteroids and asteroid belts are a staple of science fiction stories. Asteroids play several potential roles in science fiction, most notably as places which human beings might colonize, as resources for extracting minerals, as a hazard encountered ...
*
Diogenite Diogenites are a group of the HED meteorite clan, a type of achondritic stony meteorite A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage t ...
*
Eucrite Eucrites are achondrite, achondritic stony meteorites, many of which originate from the surface of the asteroid 4 Vesta and as such are part of the HED meteorite clan. They are the most common achondrite group with well over 100 distinct finds at ...
* Former classification of planets *
Howardite Howardites are achondrite, achondritic stony meteorites that originate from the surface of the asteroid 4 Vesta, and as such are part of the HED meteorite clan. There are about 200 distinct members known. Characteristics They are a regolith breccia ...
*
Vesta familyThe Vesta family (adj. ''Vestian''; ) is a family In human society, family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of familie ...

Vesta family
(vestoids) *
List of tallest mountains in the Solar System This is a list of the tallest mountains in the Solar System. The tallest peak or peaks on worlds where significant mountains have been measured are given. For some worlds, the tallest peaks of different classes are also listed. At , the enormous ...


Notes


References


General references

* ''The Dawn Mission to Minor Planets 4 Vesta and 1 Ceres'', Christopher T. Russell and Carol A. Raymond (Editors), Springer (2011), * Keil, K.; ''Geological History of Asteroid 4 Vesta: The Smallest Terrestrial Planet'' in ''Asteroids III'', William Bottke, Alberto Cellino, Paolo Paolicchi, and Richard P. Binzel, (Editors), University of Arizona Press (2002),


External links


Interactive 3D gravity simulation of the Dawn spacecraft in orbit around Vesta
* * * *
Vesta Trek – An integrated map browser of datasets and maps for 4 Vesta

JPL Ephemeris
* NASA'
Dawn Spacecraft
* Views of the Solar System


HubbleSite
Hubble Maps the Asteroid Vesta
''Encyclopædia Britannica'', Vesta – full article

HubbleSite
short movie composed from
Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope A space telescope or space observatory is a telescope in outer space used to observe astronomical objects. Suggested by Lyman Spitzer in 1946, the first ...

Hubble Space Telescope
images from November 1994. * Adaptive optics views of Vesta fro
Keck Observatory

4 Vesta images at ESA/Hubble

Hubble views of Vesta on the Planetary Society Weblog
''(includes animation)''
Dawn at Vesta
(NASA press kit on Dawn's operations at Vesta)
NASA video

Vesta atlas



PDS Small Bodies Image Browser

DLR public Dawn products site
* News articles *
Differentiated interior
of Vesta *
HubbleSite
Hubble Reveals Huge Crater on the Surface of the Asteroid Vesta ** Horton, Adam

14 December 2014. * * {{DEFAULTSORT:000004 4 Vesta, Vesta Vesta Vesta 20110716 Former dwarf planets Former dwarf planet candidates Articles containing video clips V-type asteroids (Tholen) V-type asteroids (SMASS) 1800s in science, 18070329 Astronomical objects discovered in 1807, 18070329