10 Hygiea

Fourth-largest asteroid October 2019 yes possible dwarf planet 10 Hygiea 24px|🝹|class=skin-invert (historical astronomical)24px|⯚|class=skin-invert (modern astrological) SPHERE image of Hygiea.jpg Hygiea's southern hemisphere imaged by the Very Large Telescope in July 2017 Annibale de Gasparis Astronomical Observatory of Capodimonte 12 April 1849 h aɪ ˈ dʒ iː əHygeia Hygiean h aɪ ˈ dʒ iː ə nhygeian (10) Hygiea A849 GAA900 GA Hygieia Main belt (outer)Hygiea family 5 May 2025 (JD 2460800.5) 0 3.488 AU e6km unit on 0 2.799 AU e6km unit on 0 9 February 2028 3.144 AU e6km unit on 0 0.1096 5.57 yr (2,036 days) 181.38° 0.17683 ms / day 3.832° to ecliptic 283.13° 312.71° 3.1418 0.1356 5.1039° 64.6218 128.544 −96.9024 450 x 430 x 424 km(±10 x 10 x 20 km)18 433 8 km (2021)6434 14 km (2020)136 0.06 0.05Flattening derived from the maximum aspect ratio (c/a): , where (c/a) 0.94 0.05.6 8.236 0.021 19 kg14mass Calculated from its standard gravitational parameter GM = 5.497 0.014 km3 s2. 1.94 0.11 g/cm314Assuming a diameter of 433 ± 8 km. 0.082 217m/s2 (average) 0.082 217km/s (average) 13.82559 0.00005 h13618 319 3 °136 -46 3 °136 306 3 °18 -29 3 °18 120 ° to ecliptic18 0.063 (2021)60.072 (2020)139 Kelvin ≈100 163 230 5 C 9.0 to 12.0 5.65 0.1 to 0.3 arcseconds 10 Hygiea is a large asteroid in the outer region of the main asteroid belt, between the orbits of Mars and Jupiter. It was the tenth known asteroid, discovered on 12 April 1849 by Italian astronomer Annibale de Gasparis at the Astronomical Observatory of Capodimonte in Naples, Italy. It was named after Hygieia, the Greek goddess of health. It is the fourth-largest main-belt asteroid by both volume and mass, with a mean diameter of 433 km mi and a mass constituting 3% of the main asteroid belt's total mass. Hygiea has a nearly spherical shape, with two known craters about 100 and 180 km mi in diameter. Because of its shape and large size, some researchers consider Hygiea a possible dwarf planet. Hygiea has a dark, carbonaceous surface consisting of hydrated and ammoniated silicate minerals, with carbonates and water ice. Hygiea's subsurface likely contains a large fraction of water ice. These characteristics make Hygiea very similar to the main-belt dwarf planet Ceres, which suggests the two objects have similar origins and evolutionary histories.2 Hygiea is the parent body of the Hygiea family, an asteroid family comprising over 7,000 known asteroids that share similar orbital and compositional characteristics with Hygiea. The Hygiea family is believed to have formed by a giant impact on Hygiea about 2 to 3 billion years ago. This impact is thought to have shattered Hygiea, which led to its reaccumulation as a nearly spherical body. History Discovery Hygiea was discovered on the evening of 12 April 1849 by Italian astronomer Annibale de Gasparis at the Astronomical Observatory of Capodimonte in Naples, Italy.XV10 On that night he was using the observatory's Reichenbach equatorial telescopeThe Reichenbach equatorial telescope was the smaller of the Capodimonte Observatory's two equatorial telescopes, with an objective lens diameter of 8.3 cm in and focal length of 120 cm in.9 The Reichenbach equatorial telescope was located in the northern dome of the observatory.10 to observe a section of the sky in the 12th hour of right ascension, as part of his larger project of cataloguing stars along the ecliptic up to the 14th apparent magnitude.XV–XVI10 While comparing his observations to the Berlin Academy's star chart,10The Berlin Academy star chart, which was published in years between 1830 and 1859, was compiled by a collaboration of astronomers who were each allotted a section of the sky spanning one hour of right ascension.367 The stars in the 12th (XXII) hour of right ascension were charted by Carl August von Steinheil,368 whose map aided de Gasparis's discovery of Hygiea.126XVI de Gasparis noticed a starlike object between magnitude 9 and 10 which was not recorded before.12610Hygiea was located at the 12th hour of right ascension in the sky at the time of its discovery. Although poor weather prevented further observations for a few days, de Gasparis reobserved the object on 14 and 17 April and confirmed it had moved between these dates.126 Judging by how much the object had moved, de Gasparis concluded it must be another new planetAsteroids were referred to as "planets" at the time of Hygiea's discovery. These would eventually be recategorized as "minor planets". between the orbit of Mars and Jupiter.126 De Gasparis announced his discovery to Erasmo Fabri Scarpellini,28 secretary of the Correspondenza Scientifica bulletin at Rome, Italy,126 who in turn passed on the news to Heinrich Christian Schumacher, who published it in the Astronomische Nachrichten journal on 11 May 1849. Hygiea was the first asteroid discovered by de Gasparis and the tenth asteroid discovered in history.80 He would later discover another six asteroids between 1850 and 1853 and two more during the 1860s. Name De Gasparis invited Ernesto Capocci Belmonte, his friend and director of the Capodimonte Observatory, to assign a name to the asteroid as gratitude for his help and advice.XVI10 Capocci suggested the name Igea—the Italian spelling of Hygieia, the Greek goddess of health and daughter of Asclepius.10 De Gasparis added the adjective Borbonica to Capocci's suggested name, to honor King Ferdinand II of the Bourbons of Naples who ruled the Kingdom of the Two Sicilies and supported the work of the Capodimonte Observatory.XVI Together, de Gasparis and Capocci proposed the name Igea Borbonica ("Bourbon Hygieia") in a letter forwarded to Ferdinand II on 8 May 1849.10 De Gasparis's commemoration of the Bourbons may have helped him and Capocci circumvent punishment for their participation in the liberal movements of 1848. The name Igea Borbonica was not mentioned in the first communications to the European scientific community.10 When English astronomer John Herschel received the news of Hygiea's discovery from his Neapolitan colleagues,10 he suggested that Parthenope would be an apt name for de Gasparis's discovery, as it comes from the siren who founded Naples in Greek mythology.127 In a letter written to English mathematician Augustus De Morgan in April 1849, Herschel wrote: No name has yet been mentioned. What do you think of Parthenope (being a Neapolitan?) I should think it will occur as a matter of course to Gasparis if he has any classical reading. John Herschel in a letter to Augustus De Morgan (April 1849)10–11 Herschel corresponded with other European scientists and astronomers to hear their thoughts on the name Parthenope for de Gasparis's discovery, although by the time he reached out to de Gasparis, Hygiea had already been named one month earlier. When Schumacher, editor of Astronomische Nachrichten, learned of the name proposed by de Gasparis and Capocci, he complained in a letter addressed to Herschel on 26 June 1849 that it had the Italian spelling instead of the Latin form, as conventionally done for all the other planets. Regardless, de Gasparis recognized Herschel's suggestion and expressed desire to realize Herschel's wish.167 On 11 May 1850, de Gasparis discovered the asteroid 11 Parthenope and acknowledged Herschel for the name in his announcement. There are multiple variations on the Latin spelling of Hygiea, including Hygièa, Hygia, and Hygea. The modern English form Hygiea is a less common variant of the goddess's name, which in Greek is Ὑγίεια (Hygieia) or Ὑγεῖα (Hygeia). The name was often spelled Hygeia (and occasionally Hygea80) by astronomers during the early 1850s, though by the 1860s, the spelling Hygiea became commonplace.May 2026 According to the English astronomer John Russell Hind, the adjective Borbonica had been dropped by 1852.12668–70 Symbol and designation As with the other previously discovered asteroids, Hygiea was given an astronomical symbol as a way of representing it. The symbol for Hygiea was proposed by de Gasparis in a letter addressed to Hind on 4 November 1850, in which he wrote, "The symbol of Hygeia is a serpent (like a Greek ζ) crowned with a star." Visually, de Gasparis's symbol for Hygiea is depicted as: 24px|The traditional planetary symbol for 10 Hygiea|alt=A zeta-shaped serpent crowned with a star|class=skin-invert (U+1F779 🝹 in Unicode 17.0).7 The serpent, particularly when drinking from a bowl, is a traditional symbol of the goddess Hygieia (cf. U+1F54F 🕏). However, perhaps due to the late announcement of Hygiea's intended symbol, it was not used in following astronomical almanacs such as the Berliner Astronomisches Jahrbuch in 1850 and the Nautical Almanac and Astronomical Ephemeris in 1852, marking the first time an asteroid was listed without its symbol in these almanacs.7 American astronomer Benjamin Apthorp Gould interpreted Hygiea's symbol as a rod of Asclepius, depicting it as a serpent coiled around a staff in a January 1852 publication of the Astronomical Journal: 24px|rod of Asclepius|class=skin-invert (U+2695 ⚕).807 Both symbols of Hygiea soon became obsolete, as the number of asteroids discovered had grown too much for each to have unique symbols.80 In 1851 Johann Franz Encke proposed a different identification system, suggesting using a number corresponding to the asteroid's order of discovery enclosed in a small circle.5 For Hygiea, it would be ⑩.80 Astronomers began adopting Encke's circled number scheme in scientific publications, though as the number of asteroids discovered grew, astronomers eventually switched to plainly writing out the asteroid's number, sometimes enclosing it in parentheses.5 This led to the modern minor-planet designation scheme, where Hygiea is referred to (10) Hygiea or 10 Hygiea. The Minor Planet Center uses the minor planet provisional designations A849 GA and A900 GA for Hygiea, though these are only retrospective extensions of the new-style provisional designation scheme established in 1925. While the provisional designation A849 GA refers to the discovery date of Hygiea, the designation A900 GA refers to the date when Hygiea was serendipitously observed and catalogued (as Arequipa 3813) by the Harvard College Observatory's photographic sky survey at Arequipa, Peru in 1900.newstyle In the new-style provisional designation scheme for pre-1925 minor planet discoveries, the designation begins with the letter A followed by three digits corresponding to the year of discovery ("A849" for 1849, and "A900" for 1900) and ends with two letters, with the first indicating the discovery date's half-month ("G" for the first half of April) and the second indicating the order of discovery in that half-month ("A" meaning first minor planet discovered in that half-month). Hygiea has seen some minor astrological use, though its symbol was confused once again, with Asclepsius's rod replaced by Mercury's caduceus: 24px|Astrological symbol for Hygiea|class=skin-invert, though in a more elaborate form (U+2BDA ⯚) than the caduceus symbol of the planet Mercury.611 The caduceus has long been mistaken for the rod of Asclepius (see caduceus as a symbol of medicine). Classification thumb|upright=1.5|This graphic used in the IAU 2006 draft proposal listed Hygiea as a potential planet.17 While the first four asteroids discovered—Ceres (1801), Pallas (1802), Juno (1804), and Vesta (1807)—were considered planets during the first half of the 19th century (with some astronomers continuing to consider them as such until the end of the century), the discovery of Hygiea occurred when the classification of asteroids was already evolving. Hygiea was referred to as a planet in the following years after its discovery, though by 1852 astronomers have also called Hygiea a minor planet127 or an asteroid.80 These terms were introduced prior to Hygiea's discovery and became more used with the discovery of more asteroids beginning in the 1850s. From the second half of the 19th century, asteroids began to be treated in a predominantly collective way, grouped according to orbital or spectral characteristics, with less attention to the individual object. In 2006, the International Astronomical Union's (IAU) committee for drafting a new definition of planet had considered classifying Hygiea among the planets or the newly-coined category of dwarf planets, if it were found that the asteroid is massive enough to be shaped predominantly by hydrostatic equilibrium.2381750 This proposal for the definition of planet has since been revised and adopted to decree that a planet must orbit the Sun, have sufficient mass to attain a spherical shape by hydrostatic equilibrium, and clear its neighbourhood; objects that satisfy all but the last criterion are considered dwarf planets.137–138 Since 2019, telescope images have resolved Hygiea's nearly spherical shape, suggesting that it may have reached hydrostatic equilibrium. Because Hygiea already orbits the Sun and is located in the asteroid belt where it has not cleared its orbital neighborhood, Hygiea's nearly spherical shape could qualify it as a dwarf planet, according to Pierre Vernazza and collaborators who studied Hygiea with telescope imaging.138–139 If so, Hygiea could be the smallest dwarf planet known. However, the IAU has not yet officially classified Hygiea as a dwarf planet.1 Orbit upright=1.3|thumb|alt=A diagram of Hygiea's orbit|Diagram of Hygiea's orbit (white), with the inner planets' and Jupiter's orbits labelled Hygiea orbits the Sun at an average distance (semi-major axis) of 3.14astronomical units (AU; 470 e6km e6mi unit or 2), which places it in the outer portion of the main asteroid belt between Mars and Jupiter.18 Hygiea has an orbital period of 5.57 Earth years and follows an elliptical orbit where its distance from the Sun ranges between 2.79 AU e6km e6mi unit 2 at perihelion to 3.49 AU e6km e6mi unit 2 at aphelion. Hygiea has a relatively low1223569 orbital inclination of 3.8° with respect to the ecliptic plane. In its current orbit, Hygiea never comes closer than 1.24 AU e6km e6mi unit to Mars and 1.54 AU e6km e6mi unit to Jupiter. Hygiea is in a three-body mean motion orbital resonance with Jupiter and Saturn.3032 In this resonance, the mean motions or orbital frequencies of Jupiter, Saturn, and Hygiea follow the relation , where a linear combination of their mean motions () with integer coefficients equals zero.303278 Simulations show that this three-body resonance leads to a chaotic evolution in Hygiea's orbit, with a short3029 Lyapunov time between 14,000 and 16,000 years.78 This means that changes in Hygiea's orbit become exponentially less predictable over this time scale.3029 Other asteroids occasionally pass close to Hygiea, sometimes close enough that their trajectories become visibly perturbed or deflected by Hygiea's gravity.31129 This allows astronomers to measure Hygiea's mass.311 A 2002 study identified 40 known asteroids that have passed within 0.05 AU e6km e6mi unit of Hygiea between 1970 and 2000.1118 Over a time span of 30 million years, Hygiea's gravitational perturbations can cause the proper semi-major axes of close-passing asteroids to change by 0.000908 AU km mi 3.5 Hygiea family thumb|upright=1.5|Location and structure of the Hygiea family Hygiea family March 2025 Hygiea is the parent body of the Hygiea family, an asteroid family comprising over 7,000 known asteroids that share similar orbital and compositional characteristics with Hygiea. The Hygiea family is the most populous asteroid family in the outer main belt, and is believed to have formed by a giant impact on Hygiea that ejected at least 1.7% of the asteroid's original mass about 2 to 3 billion years ago. The impactor that formed the Hygiea family was probably between 75 and 150 km mi in diameter. Hygiea contains almost all the mass (over 98%) of the family. Rotation right 350 10 Hygiea lightcurve TRAPPIST 2018.png Rotational light curve of Hygiea measured by the TRAPPIST telescope in 2018 Hygiea shape model rotation.gif Simulation of Hygiea's retrograde (clockwise) rotation The rotation period of Hygiea is about 13.83hours (13 hours and 49.5 minutes), with an uncertainty of 0.2 seconds.13618 This rotation period was determined via direct imaging and analysis of Hygiea's light curve, or changes in brightness over time.139 From Earth, Hygiea's brightness periodically fluctuates by up to 15% from its average value3 as albedo features on Hygiea's surface rotate in and out of view. The north pole of Hygiea's rotation axis points toward the ecliptic south, in the direction of ecliptic longitude 306 3 ° and ecliptic latitude -29 3 °.18 This means Hygiea's rotation axis is highly tilted with an obliquity of 120° with respect to the ecliptic.18 Since Hygiea's obliquity is greater than 90°, it has a retrograde rotation, meaning it rotates backwards with respect to the direction of its orbit around the Sun.54 Before it was directly imaged by telescopes in 2017–2018, Hygiea was thought to have a rotation period twice as long as the currently accepted value.139 The first measurements of Hygiea's rotation period beginning in the 1950s reported 18 hours538–53953 while studies from 1991 and onward reported 27.6 hours.139 These past observations did not collect enough datapoints to produce reliable light curves, which led to these inaccurate rotation period measurements.139 Size and mass thumb|upright=1.5|Relative sizes of the four largest asteroids. Hygiea is furthest right. Hygiea is the fourth-largest main-belt asteroid by both volume and mass, with a volume-equivalent mean diameter of 433 ± 8 km mi 0 and a mass of 8.236 0.021 19 kg.14mass Compared to the largest asteroid Ceres, Hygiea is less than half its diameter and is roughly 10% as massive.15 Hygiea constitutes 3% of the total mass of the entire main belt736 and is the largest asteroid in the outer main belt.18 The four largest asteroids (Ceres, Pallas, Vesta, and Hygiea) together make up a little more than half of the entire main belt's mass.738 These four largest asteroids have sometimes been collectively referred to as the "Big Four" by astronomers, although historically this term meant the first four asteroids discovered (Ceres, Pallas, Juno, and Vesta).26 Hygiea was not recognized as the fourth-largest asteroid until 1974, when David Morrison measured its diameter and albedo for the first time by using its infrared thermal emission.211 The best estimate for Hygiea's diameter was measured via direct imaging using the Very Large Telescope (VLT) in Chile, whose atmospheric turbulence-correcting adaptive optics could resolve the asteroid in high angular resolution.1 Hygiea's mass was measured by observing how its gravity deflects the paths of other asteroids that pass near it.18–19 This requires an extensive number of observations with accurate positional measurements of the deflected asteroid before and after its close approach.1311 The measurement of Hygiea's mass through this method was first attempted in 1986, with the analysis of a past close approach by the asteroid 829 Academia (which passed 0.006 AU e3km e3mi unit or from Hygiea on 19 May 1927705).311–313 Hygiea's mass has since been refined with additional asteroid close approaches and more accurate observations.70518–19 Geology Shape, craters, and topography thumb|upright=1.5|Model of Hygiea's nearly spherical shape as seen from three mutually orthogonal views thumb|upright=1.2|Hygiea's two large craters "Serpens" and "Calix" identified in VLT images from 2017. A bright spot is visible to the left of Serpens. Hygiea is a nearly spherical or ellipsoidal object137 whose diametric dimensions are 450 x 430 x 424 km mi, with an uncertainty of ±10 km mi for the equatorial axes and ±20 km mi for the polar axis.136 It is the second-most spherical main-belt asteroid after Ceres.5 The nearly spherical shape of Hygiea suggests it may be in hydrostatic equilibrium, having attained its shape by its own gravity.138 Specifically, Hygiea's polar flattening and specific angular momentum closely matches that of a Maclaurin spheroid, which is the shape assumed by a rotating self-gravitating fluid in hydrostatic equilibrium.1377 In contrast to the larger asteroid Vesta, Hygiea lacks large impact craters or basins that would otherwise deform its shape from a sphere.137 Only two craters on Hygiea have been confidently identified in VLT imaging, with their respective diameters being 180 ± 15 km mi and 97 ± 10 km mi.13911 Both craters appear to have central peaks.11 Vernazza and collaborators who studied these images have informally named the larger crater "Serpens" and smaller crater "Calix", after the Latin words for 'snake' and 'cup', respectively.11 These names, which are not approved by the IAU, were chosen because their eponyms commonly appear in symbols of Hygiea.11 Besides Serpens and Calix, VLT images of Hygiea show no obvious or bowl-shaped craters larger than 30 km mi in diameter.139 Ceres similarly lacks large bowl-shaped craters and is instead dominated by flat-floored complex craters, which are difficult to see from Earth—this may be the case for Hygiea.1399 An abundance of flat-floored craters on Hygiea could indicate a water ice-rich subsurface, which would allow for the relaxation of its surface topography.139 Although Hygiea lacks major impact basins, the existence of the Hygiea family points to a major collisional event in its past. Rather than leaving a giant impact basin like on Vesta, the impact is thought to have completely shattered Hygiea, which erased all of its pre-existing surface features.137 Simulations of the giant impact show that most of Hygiea's debris reaccumulated into a fluid-like body, which was able to relax into a sphere by its own gravity.137–138 The present-day shape of Hygiea suggests it solidified around four hours after the impact.1378 Other large asteroids that are parents of asteroid families, such as 8 Flora and 31 Euphrosyne, have also been found to show roughly spherical shapes and are thus believed to have undergone similar collisional disruption and reaccumulation.5 Surface Albedo, temperature, and regolith thumb|upright=1.5|Albedo and shadow map of Hygiea's southern hemisphere in an equirectangular projection, constructed from VLT images.13910 A bright spot is present at longitude 290 ° and latitude -30 °.139 The surface of Hygiea is dark,1 with an average visual geometric albedo estimated between 6.3% and 7.2%.6139 The apparent brightness or reflectance varies across Hygiea's surface due to variations in albedo and shadows cast by topographic features.139 VLT images of Hygiea show several bright spots on its surface, with the brightest one located on Hygiea's southern hemisphere at longitude 290 ° and latitude -30 °.139 The brightest spot is 10% brighter than the average reflectance of Hygiea's surface.139 A large dark region is present along Hygiea's equator at longitude 60 ° and latitude 0 °, though it is most likely a shadowed region.139 The albedo and reflectance variation across Hygiea's surface resembles those of Ceres.139 The temperature on Hygiea's surface depends on the asteroid's rotation, distance from the Sun,336 and the properties of its surface regolith.194 While the surface of Hygiea have been observed to reach temperatures as high as 230 K C F at the subsolar point,204394 the surface cools down as it rotates away from the Sun, which averages out the temperature.196 Between Hygiea's perihelion and aphelion distances, the average temperature can range from 150 to 180 K C F.434 At Hygiea's semi-major axis, the average temperature would be 163 K C F.336 Astronomers have described Hygiea as a "fairly dusty object",199120 with a regolith layer consisting mostly of fine dust rather than coarse rock.335 This fine regolith has a low thermal inertia, meaning it radiates away heat more easily and leads to cooler temperatures on Hygiea's surface.194–195 The regolith of Hygiea may be dustier (and thus finer4) than that of Earth's Moon, which could imply a more mature regolith199 that has experienced more space weathering.4 The regolith layer of Hygiea is estimated to be at least 8 cm in deep.335203 These properties of Hygiea's regolith were inferred from the asteroid's lower-than-expected temperature and thermal emission in infrared, submillimetre, and microwave wavelengths.195335 Composition thumb|upright=2|The similar spectra of Ceres (red) and Hygiea (blue) in visible to near-infrared wavelengths indicate they have similar compositions. Both spectra show absorption signatures of hydrated and ammoniated phyllosilicates. Hygiea is a carbonaceous asteroid whose surface is largely composed of hydrated and ammoniated silicate minerals (phyllosilicates) and carbonates,1, 4 with hints of water ice.9 This composition is inferred from spectroscopic observations of Hygiea, whose visible and near-infrared spectrum characterize it as a C-type asteroid.203 More broadly, it makes Hygiea a member of the C spectral complex,1 which is common in the outer main belt where Hygiea resides.18 The spectrum and composition of Hygiea's surface is very similar to those of carbonaceous chondrite meteorites and Ceres,1 which has led some astronomers to call Hygiea a "primitive" object209 and a "virtual spectral twin of Ceres".2 Hygiea's resemblance to carbonaceous chondrites (particularly CM chondrites1) suggests it shares a similar history of having undergone little thermal alteration and some aqueous alteration of its original minerals, hence its likely primitive nature.209 Slight differences between the near-infrared spectra of Hygiea and Ceres indicate they have slightly different concentrations of hydrated and ammoniated minerals.912 High resolution near-infrared spectroscopy by the James Webb Space Telescope has found that Hygiea's phyllosilicates are magnesium-rich5, 15 and appear to match ammoniated saponite.12 Ground-based observations have shown that the near-infrared spectrum of Hygiea varies over time, which implies there is compositional variation across Hygiea's surface.918 A 2011 study by Vladimir Busarev observed Hygiea's spectral type changing between C, B, and F over the course of its rotation,47–48 which he interpreted as an indication of local dehydration of Hygiea's surface material,5018 possibly as a result of heating by impacts.15 A 2019 study by Andrew Rivkin and colleagues reported changes in the 3.1 um absorption feature in Hygiea's near-infrared spectrum over a time scale of years.1401 While this absorption feature is often attributed to ammoniated minerals,1394, 1403 its variations could also correspond to either hydrated minerals or potentially water ice frost.1394, 14019 Rivkin and colleagues speculated that the variations could be caused by exposed subsurface material on some parts of Hygiea's surface,1405 although they do not appear to be correlated with one particular surface location.1403 Density and interior Hygiea's bulk density has been estimated as either 1.944 0.250 g/cm3 or 2.06 0.20 g/cm3, based on measurements of its diameter and mass from 2020 and 2021, respectively.136–1376 Hygiea's bulk density is similar to that of Ceres (2.16 g/cm3),137 which together with Hygiea's large size suggests it could have a differentiated interior.7, 910 Hygiea likely has a water ice-rich subsurface, as hinted by Hygiea's bulk density, spectroscopic detections of water ice, and its lack of large, bowl-shaped craters.1397 Assuming the higher density estimate of 2.06 0.20 g/cm3, Hygiea would be among the denser members of the largest C-type asteroids (diameters larger than 300 km mi or), whose densities range between 1.5 to 2.16 g/cm3 and may have negligible interior macroporosities, according to Vernazza and colleagues.12 They further speculated that the higher densities of Hygiea and other large C-type asteroids may be due to a more lithified or compacted interior, as a result of significant aqueous alteration.12 Observation and exploration Observation thumb|Image of 10 Hygiea taken by the 2MASS survey March 2025 Despite its size, Hygiea appears very dim when observed from Earth. This is due to its dark surface and its position in the outer main belt. For this reason, six smaller asteroids were observed before Annibale de Gasparis discovered Hygiea on 12 April 1849. Although it is the largest body in its region, due to its dark surface and farther-than-average distance from the Sun, Hygiea appears very dim when observed from Earth. In fact, it is the third dimmest of the first twenty-three asteroids discovered, with only 13 Egeria and 17 Thetis having lower mean opposition magnitudes. At most oppositions, Hygiea has a magnitude of around +10.2, which is as much as four orders fainter than Vesta, and observation calls for at least a 4 in mm on telescope to resolve. However, at a perihelic opposition, Hygiea can reach +9.1 magnitude and may just be resolvable with 10 × 50 binoculars, unlike the next two largest asteroids in the asteroid belt, 704 Interamnia and 511 Davida, which are always beyond binocular visibility. A total of 17 stellar occultations by Hygiea have been tracked by Earth-based astronomers, including two (in 2002 and 2014) that were seen by a large number of observers. The observations have been used to constrain Hygiea's size, shape and rotation axis. The Hubble Space Telescope has resolved the asteroid and ruled out the presence of any orbiting companions larger than about 16 km mi in diameter. Exploration Hygiea has not been explored by any space probe. In 2006, Mark V. Sykes and others from the Planetary Science Institute proposed the Exploring the Very Earliest Epoch (EVE) mission to NASA, as part of the Discovery Program. The proposal, which did not get approved, suggested launching a copy of the Dawn probe to Hygiea in October 2011 and arriving to the asteroid via rendezvous in 2021.1–2 In 2013,431 Pierre Vernazza and Philippe Lamy proposed the medium-class mission INSIDER for the European Space Agency's Space Programme. The proposal, which also did not get approved, suggested rendezvousing and orbiting around two or three large main-belt asteroids before releasing one or two landers. Hygiea and 24 Themis were among the potential targets of the INSIDER mission concept. The exploration of primitive main-belt asteroids like Hygiea could provide clues to the processes that led to the formation of the Solar System.1 See also 704 Interamnia – the fifth-largest main-belt asteroid, whose shape is close to hydrostatic equilibrium 65 Cybele – one of the largest main-belt asteroids, whose shape is also close to hydrostatic equilibrium Hygiea family – group of asteroids likely formed by a collision involving Hygiea List of former planets List of gravitationally rounded objects of the Solar System Notes lower-alpha References 2025-01-13 last obs. JPL Small-Body Database Lookup: 10 Hygiea (A849 GA) https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=20000010 Jet Propulsion Laboratory 28 March 2025 (10) Hygiea = A849 GA = A900 GA https://www.minorplanetcenter.net/db_search/show_object?object_id=10 Minor Planet Center 28 March 2025 AstDyS-2 Hygiea Synthetic Proper Orbital Elements Asteroids Dynamic Site Department of Mathematics, University of Pisa, Italy https://newton.spacedys.com/astdys/index.php?pc=1.1.6&n=10 13 April 2025 live https://web.archive.org/web/20241219052502/https://newton.spacedys.com/astdys/index.php?n=10&pc=1.1.6 19 December 2024 JPL Horizons On-Line Ephemeris for 10 Hygiea (A849 GA) on 1849 Apr 12–1849 Apr 13 https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND='Hygiea'&TABLE_TYPE='OBSERVER'&START_TIME='1849-04-12'&STOP_TIME='1849-04-13'&STEP_SIZE='1d'&CENTER='500@399'&QUANTITIES='1' JPL Horizons On-Line Ephemeris System Jet Propulsion Laboratory 26 March 2025 Ephemeris Type: Observer and Center: 500@399 (geocentric) JPL Horizons On-Line Ephemeris for 10 Hygiea (A849 GA) on 2020 Jan 1–2030 Jan 1 (apparent magnitude and constellations shown) https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%27Hygiea%27&TABLE_TYPE=%27OBSERVER%27&START_TIME=%272020-01-01%27&STOP_TIME=%272030-01-01%27&STEP_SIZE=%2710d%27&CENTER=%27500@399%27&QUANTITIES=%2713,19,20%27 JPL Horizons On-Line Ephemeris System Jet Propulsion Laboratory 2025-10-17 Ephemeris Type: Observer and Center: 500@399 (geocentric) H. C. Schumacher Heinrich Christian Schumacher Planeten Circular https://articles.adsabs.harvard.edu/pdf/1849AN.....28..391A Astronomische Nachrichten de 11 May 1849 28 672 391 10.1002/asna.18490282604 1849AN.....28..391A Salvatore Murena Annali Civili del Regno delle Due Sicilie it Cenno de' lavori accademici e dell'azione governativa ne' reali domini continentali dal 1848 al primo semestre del 1852 https://play.google.com/books/reader?id=8R9EAAAAYAAJ&pg=GBS.PR2&hl=en Vincenzo de Ritis 1852 XIII–XXI 46 Tipografia del Real ministero degli affari interni Naples, Italy live https://web.archive.org/web/20241127115751/https://books.google.it/books?id=8R9EAAAAYAAJ&dq 27 November 2024 The Solar System: Descriptive Treatise Upon the Sun, Moon, and Planets, Including an Account of All the Recent Discoveries en Chapter VIII. The Minor or Ultra-Zodiacal Planets. https://archive.org/details/solarsystemdescr00hind/page/126/mode/2up John Russell Hind John Russell Hind 1852 126 G. P. Putnam's Sons New York, United States Rock Legends: The Asteroids and Their Discoverers Ceres Ferdinandea: Ferdinand's Ceres http://ndl.ethernet.edu.et/bitstream/123456789/75660/1/293.pdf#page=77 Paul Murdin 2016 68–70 978-3-319-31836-3 Springer International Publishing Switzerland Celestial mechanics. A survey of the status of the determination of the general perturbations of the minor planets en (10) Hygiea https://archive.org/details/celestialmechani00natirich/page/28/mode/2up Armin Otto Leuschner 1922 94 National Research Council of the National Academy of Sciences Washington, D. C., United States Derek Jones Akademische Sternkarten, Berlin 1830—59 https://articles.adsabs.harvard.edu/pdf/2002HiA....12..367J Highlights of Astronomy 2002 12 367–370 free 10.1017/S1539299600013770 2002HiA....12..367J William B. Ashworth Jr. Scientist of the Day - Annibale de Gasparis https://www.lindahall.org/about/news/scientist-of-the-day/annibale-de-gasparis/ Linda Hall Library 9 November 2022 27 March 2025 live https://web.archive.org/web/20250327192326/https://www.lindahall.org/about/news/scientist-of-the-day/annibale-de-gasparis/ 27 March 2025 Maruo Gargano Annibale de Gasparis, the sublime calculator of Parthenope's sky Bulletin of Regional Natural History April 2023 3 1 1–24 free 10.6093/2724-4393/9975 Paolo Palma A Parthenope in the sky https://royalsociety.org/blog/2019/11/a-parthenope-in-the-sky/ The Royal Society 5 November 2019 27 March 2025 live https://web.archive.org/web/20250116095304/https://royalsociety.org/blog/2019/11/a-parthenope-in-the-sky/ 16 January 2025 J. L. Hilton When did asteroids become minor planets? http://aa.usno.navy.mil/faq/docs/minorplanets.php U.S. Naval Observatory 16 November 2007 27 March 2025 dead https://web.archive.org/web/20070921162818/http://aa.usno.navy.mil/faq/docs/minorplanets.php 21 September 2007 Thomas Hockey The Biographical Encyclopedia of Astronomers Gasparis, Annibale de https://link.springer.com/referenceworkentry/10.1007/978-0-387-30400-7_502 Ennio Badolati Springer, New York, NY 2007 408 10.1007/978-0-387-30400-7_502 978-0-387-30400-7 Santi Mancuso DE GASPARIS, Annibale https://www.treccani.it/enciclopedia/annibale-de-gasparis_(Dizionario-Biografico) Dizionario Biografico degli Italiani Treccani 36 1988 27 March 2025 it Annibale de Gasparis Capocci, Ernesto Lettera a Ernesto Capocci https://www.beniculturali.inaf.it/opac/archivi/lettera-a-ernesto-capocci_22774# Archivio di Stato di Napoli Ministero Pubblica Istruzione. F. 428, f. 3 8 May 1849 27 March 2025 Gavin Jared Bala Kirk Miller Unicode request for historical asteroid symbols https://www.unicode.org/L2/L2023/23207-historical-asteroids.pdf 18 September 2023 unicode.org Unicode 26 September 2023 David Faulks Additional Symbols for Astrology, Revised https://www.unicode.org/L2/L2016/16080r-add-astrology.pdf 28 May 2016 unicode.org Unicode 22 May 2023 live https://web.archive.org/web/20220511233510/https://www.unicode.org/L2/L2016/16080r-add-astrology.pdf 11 May 2022 Alchemical Symbols https://www.unicode.org/charts/PDF/U1F700.pdf unicode.org The Unicode Consortium 2025 17 September 2025 Annibale de Gasparis Letter to Mr. Hind, from Professor Annibale de Gasparis Monthly Notices of the Royal Astronomical Society November 1850 11 1 free 10.1093/mnras/11.1.1a 1850MNRAS..11....1D The symbol of Hygeia is a serpent (like a Greek ζ) crowned with a star. James Ferguson Observations of Astræa and Hygea https://articles.adsabs.harvard.edu/pdf/1850AJ......1...74F The Astronomical Journal June 1850 1 10 74–76 10.1086/100046 1850AJ......1...74F B. A. Gould On the symbolic notation of the asteroids https://articles.adsabs.harvard.edu/pdf/1852AJ......2...80G The Astronomical Journal January 1852 2 80 10.1086/100212 1852AJ......2...80G ADS Search Query: "hygeia" OR "hygiea" https://ui.adsabs.harvard.edu/search/fq=%7B!type%3Daqp%20v%3D%24fq_database%7D&fq_database=(database%3Aastronomy%20OR%20database%3Aphysics)&p_=0&q=%22hygeia%22%20OR%20%22hygiea%22&sort=date%20asc%2C%20bibcode%20asc Astrophysics Data System SAO/NASA 28 March 2025 Jared Savage History of the Bowl of Hygeia award https://www.drugtopics.com/view/history-bowl-hygeia-award Drug Topics 7 October 2002 28 March 2025 live https://web.archive.org/web/20240623122202/https://www.drugtopics.com/view/history-bowl-hygeia-award 23 June 2024 Henry George Liddell Robert Scott A Greek-English Lexicon Ὑγίεια https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aalphabetic+letter%3D*u%3Aentry+group%3D2%3Aentry%3Du%28gi%2Feia%5E Perseus Digital Library 28 March 2025 live https://web.archive.org/web/20221205204914/https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aalphabetic+letter%3D*u%3Aentry+group%3D2%3Aentry%3Du%28gi%2Feia%5E 5 December 2022 Henry George Liddell Robert Scott A Greek-English Lexicon ὑγεῖα https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aalphabetic+letter%3D*u%3Aentry+group%3D2%3Aentry%3Du%28gei%3Da Perseus Digital Library 28 March 2025 live https://web.archive.org/web/20221205204638/https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aalphabetic+letter%3D*u%3Aentry+group%3D2%3Aentry%3Du%28gei%3Da 5 December 2022 Charlton T. Lewis Charles Short A Latin Dictionary Hygēa or Hygīa (Hygĭeia) https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0059%3Aalphabetic+letter%3DH%3Aentry+group%3D22%3Aentry%3DHygea Perseus Digital Library 28 March 2025 live https://web.archive.org/web/20240512221120/https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0059%3Aalphabetic+letter%3DH%3Aentry+group%3D22%3Aentry%3DHygea 12 May 2024 New- And Old-Style Minor Planet Designations https://www.minorplanetcenter.net/iau/info/DesDoc.html Minor Planet Center 28 March 2025 live https://web.archive.org/web/20210506221829/https://www.minorplanetcenter.net/iau/info/DesDoc.html 6 May 2021 M. Ebell Photographische Aufnahmen von kleinen Planeten in Arequipa https://articles.adsabs.harvard.edu/pdf/1909AN....179..207E Astronomische Nachrichten November 1908 179 13 207 10.1002/asna.19081791306 1908AN....179..207E Willi Strobel Identifizierungsnachweis der Kleinen Planeten https://wwwadd.zah.uni-heidelberg.de/publikationen/vhd/vhd009/fulltext/gifframe.htm Astronomisches Rechen-Institut, Heidelberg 1963 9 13 Curtis Peebles Asteroids: a history https://archive.org/details/asteroidshistory00curt Smithsonian Institution Press 2000 1-56098-389-2 David A. Weintraub Is Pluto a Planet?: A Historical Journey through the Solar System https://dokumen.pub/is-pluto-a-planet-a-historical-journey-through-the-solar-system-with-a-new-postscript-by-the-authornbsped-9781400852970.html Princeton University Press 2014 238 978-1-4008-5297-0 dead https://web.archive.org/web/20250329174547/https://dokumen.pub/is-pluto-a-planet-a-historical-journey-through-the-solar-system-with-a-new-postscript-by-the-authornbsped-9781400852970.html 29 March 2025 O. Gingerich Owen Gingerich Planet Definition Q & A Factsheet https://www.iau.org/static/publications/ga_newspapers/20060812.pdf#page=17 Dissertatio CVM Nvncio Sidereo III International Astronomical Union 12 August 2006 3 17 13 March 2007 dead https://web.archive.org/web/20150315084508/http://www.iau.org/static/publications/ga_newspapers/20060812.pdf 15 March 2015 Lars Lindberg Christensen Helen Sim Raquel Yumi Shida Nadja Wolf Lars Holm Nielsen The public communication at the IAU GA 2006 https://www.iau.org/static/public_press/iau_po_report.pdf#page=50 IAU XXVIth General Assembly International Astronomical Union 2006 26 50 29 March 2025 dead https://web.archive.org/web/20130501174441/https://www.iau.org/static/public_press/iau_po_report.pdf#page=50 1 May 2013 ESO Telescope Reveals What Could be the Smallest Dwarf Planet yet in the Solar System https://www.eso.org/public/news/eso1918/ European Southern Observatory eso1918 28 October 2019 29 March 2025 live https://web.archive.org/web/20191101013211/https://www.eso.org/public/news/eso1918/ 1 November 2019 John Timmer Collision liquified the 4th-largest asteroid, turning it into a dwarf planet https://arstechnica.com/science/2019/10/collision-liquified-the-4th-largest-astroid-turning-it-into-a-dwarf-planet/ ArsTechnica 29 October 2019 4 April 2025 live https://web.archive.org/web/20230606153105/https://arstechnica.com/science/2019/10/collision-liquified-the-4th-largest-astroid-turning-it-into-a-dwarf-planet/ 6 June 2023 Phil Plait New observations show the asteroid Hygiea is round! https://www.syfy.com/syfy-wire/new-observations-show-the-asteroid-hygiea-is-round Syfy Wire 26 October 2019 5 April 2025 live https://web.archive.org/web/20211021152632/https://www.syfy.com/syfy-wire/new-observations-show-the-asteroid-hygiea-is-round 21 October 2021 etal J. Hanuš P. Vernazza M. Viikinkoski M. Ferrais N. Rambaux E. Podlewska-Gaca (704) Interamnia: A transitional object between a dwarf planet and a typical irregular-shaped minor body Astronomy & Astrophysics January 2020 633 A65 17 free 10.1051/0004-6361/201936639 1911.13049 2020A&A...633A..65H 208512707 etal P. Vernazza L. Jorda P. Ševeček M. Brož M. Viikinkoski J. Hanuš A basin-free spherical shape as an outcome of a giant impact on asteroid Hygiea https://www.eso.org/public/archives/releases/sciencepapers/eso1918/eso1918a.pdf Nature Astronomy 4 136–141 10.1038/s41550-019-0915-8 10045/103308 February 2020 2 2020NatAs...4..136V 209938346 free live https://web.archive.org/web/20201111195300/https://www.eso.org/public/archives/releases/sciencepapers/eso1918/eso1918a.pdf 11 November 2020 etal P. Vernazza L. Jorda P. Ševeček M. Brož M. Viikinkoski J. Hanuš A basin-free spherical shape as an outcome of a giant impact on asteroid Hygiea (Supplementary Information) https://static-content.springer.com/esm/art%3A10.1038%2Fs41550-019-0915-8/MediaObjects/41550_2019_915_MOESM1_ESM.pdf Nature Astronomy 4 136–141 10.1038/s41550-019-0915-8 10045/103308 February 2020 2020NatAs...4..136V 209938346 free live https://web.archive.org/web/20211129130638/https://static-content.springer.com/esm/art%3A10.1038%2Fs41550-019-0915-8/MediaObjects/41550_2019_915_MOESM1_ESM.pdf 29 November 2021 etal P. Vernazza M. Ferrais L. Jorda J. Hanuš B. Carry M. Marsset VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis Astronomy & Astrophysics 654 A56 free 10.1051/0004-6361/202141781 October 2021 A56 2021A&A...654A..56V 239104699 10261/263281 free Asteroid 10 Hygiea at opposition https://in-the-sky.org/news.php?id=20170629_14_100 https://web.archive.org/web/20211127152145/https://in-the-sky.org/news.php?id=20170629_14_100 dead 27 November 2021 Ford D. in-the-sky.org 2017-06-29 2019-03-14 The Brightest Asteroids The Jordanian Astronomical Society Odeh M. http://jas.org.jo/ast.html 2008-05-21 https://web.archive.org/web/20080511115437/http://www.jas.org.jo/ast.html 2008-05-11 What Can I See Through My Scope? Ballauer Observatory 2004 http://www.allaboutastro.com/Articlepages/whatcanisee.html 2008-07-20 https://web.archive.org/web/20130622002417/http://www.allaboutastro.com/Articlepages/whatcanisee.html 2013-06-22 http://www.lpi.usra.edu/books/AsteroidsIII/pdf/3008.pdf Asteroid Masses and Densities Hilton J. L. U.S. Naval Observatory Lunar and Planetar Institute 2008-08-26 https://web.archive.org/web/20080819191809/http://www.lpi.usra.edu/books/AsteroidsIII/pdf/3008.pdf 2008-08-19 etal Storrs A. D. Wells E. N. Zellner B. H. Stern A. Durda D. D. Imaging Observations of Asteroids with HST http://articles.adsabs.harvard.edu//full/1999BAAS...31Q1089S/0001089.000.html Bulletin of the American Astronomical Society 31 1089 1999 1999DPS....31.1103S 31 October 2019 31 October 2019 https://web.archive.org/web/20191031040332/http://articles.adsabs.harvard.edu//full/1999BAAS...31Q1089S/0001089.000.html live The Index of Asteroidal Occultation Results, Worldwide ver.2 Watanabe H. http://hal-astro-lab.com/data/occult-e/occult-e.html 2018-09-09 2019-10-29 2 December 2020 https://web.archive.org/web/20201202153651/http://hal-astro-lab.com/data/occult-e/occult-e.html live L. A. Mammana R. B. Orellana Búsqueda de asteroides para determinación de masa https://articles.adsabs.harvard.edu/pdf/1997BAAA...41...29M Boletín de la Asociación Argentina de Astronomía es March 1997 41 29–31 1997BAAA...41...29M D. Nesvorný A. Morbidelli Three-Body Mean Motion Resonances and the Chaotic Structure of the Asteroid Belt The Astronomical Journal December 1998 116 6 3029–3037 free 10.1086/300632 1998AJ....116.3029N 51779089 Miloš Šidlichovský On Stable Chaos in the Asteroid Belt Celestial Mechanics and Dynamical Astronomy January 1999 73 1/4 77–86 10.1023/A:1008330610152 1999CeMDA..73...77S 51779089 V. Carruba M. Huaman R. C. Domingos F. Rong Chaotic diffusion caused by close encounters with several massive asteroids. II. The regions of (10) Hygiea, (2) Pallas, and (31) Euphrosyne Astronomy & Astrophysics February 2013 550 A85 A85 free 10.1051/0004-6361/201220448 2013A&A...550A..85C 52556450 11449/74580 free V. Carruba An analysis of the Hygiea asteroid family orbital region Monthly Notices of the Royal Astronomical Society June 2013 431 4 3557–3569 free 10.1093/mnras/stt437 2013MNRAS.431.3557C 122664149 V. Carruba R. C. Domingos M. E. Huaman C. R. dos Santos D. Souami Dynamical evolution and chronology of the Hygiea asteroid family Monthly Notices of the Royal Astronomical Society January 2014 437 3 2279–2290 free 10.1093/mnras/stt2040 1310.5982 2014MNRAS.437.2279C 37011239 Ingrid Groeneveld Ingrid van Houten-Groeneveld Gerard Kuiper Gerard Kuiper Photometric Studies of Asteroids. II. https://articles.adsabs.harvard.edu/pdf/1954ApJ...120..529G Astrophysical Journal November 1954 120 529 10.1086/145941 1954ApJ...120..529G T. Michalowski F. P. Velichko M. Lindgren T. Oja C.-I. Lagerkvist P. Magnusson The spin vector of asteroid 10 Hygiea https://articles.adsabs.harvard.edu/pdf/1991A%26AS...91...53M Astronomy & Astrophysics Supplement Series November 1991 91 1 53–59 1991A&AS...91...53M etal Marin Ferrais Emmanuël Jehin Pierre Vernazza Laurent Jorda Youssef Moulane Francisco J. Pozuelos Lightcurve Based Determination of 10 Hygiea's Rotational Period With Trappist-North and -South https://articles.adsabs.harvard.edu/pdf/2021MPBu...48..166F The Minor Planet Bulletin April 2021 48 2 166–167 2021MPBu...48..166F D. Morrison David Morrison (astrophysicist) Radiometric diameters and albedos of 40 asteroids https://articles.adsabs.harvard.edu/pdf/1974ApJ...194..203M Astrophysical Journal November 1974 194 1 203–212 10.1086/153236 1974ApJ...194..203M etal H. Scholl L. D. Schmadel S. Roser J. Ďurech M. Kaasalainen M. Delbo' The Mass of the Asteroid (10) Hygiea Derived from Observations of (829) Academia https://articles.adsabs.harvard.edu/pdf/1987A%26A...179..311S Astronomy & Astrophysics June 1987 179 1–2 311–316 1987A&A...179..311S G. Michalak Determination of asteroid masses. II. (6) Hebe, (10) Hygiea, (15) Eunomia, (52) Europa, (88) Thisbe, (444) Gyptis, (511) Davida and (704) Interamnia Astronomy & Astrophysics August 2001 374 2 703–711 free 10.1051/0004-6361:20010731 2001A&A...374..703M 123723327 A. Galád B. Gray Asteroid encounters suitable for mass determinations Astronomy & Astrophysics September 2002 391 3 1115–1122 free 10.1051/0004-6361:20020810 2002A&A...391.1115G 122537496 A. S. Rivkin R. E. Milliken J. P. Emery D. Takir B. E. Schmidt 2 Pallas and 10 Hygiea in the 3-µm spectral region https://meetingorganizer.copernicus.org/EPSC-DPS2011/EPSC-DPS2011-1271.pdf EPSC-DPS Joint Meeting 2011 Nantes, France October 2011 1271 2011epsc.conf.1271R 31 March 2025 live https://web.archive.org/web/20250331200948/https://meetingorganizer.copernicus.org/EPSC-DPS2011/EPSC-DPS2011-1271.pdf 31 March 2025 Edwin Goffin Astrometric asteroid masses: a simultaneous determination Astronomy & Astrophysics May 2014 565 A56 A56 free 10.1051/0004-6361/201322766 1402.4241 2014A&A...565A..56G 118444915 Clifford J. Cunningham Clifford Cunningham Asteroids https://books.google.com/books?id=UPgkEAAAQBAJ&pg=PA3 The Stranger Ceres Reaktion Books May 2021 9781789143591 Mark V. Sykes PSI Proposes a Distant Asteroid Mission https://www.psi.edu/sites/default/files/imported/news/newsletter/Summer06.pdf Planetary Science Institute Newsletter 2006 7 2 1–2 29 March 2025 dead https://web.archive.org/web/20150924083718/http://www.psi.edu/sites/default/files/imported/news/newsletter/Summer06.pdf 24 September 2015 P. Vernazza P. Lamy Investigation of the interior of primordial asteroids and the origin of the Earth's water: The INSIDER space mission http://www.helsinki.fi/acm2014/pdf-material/Day-5/Posters-4/VERNAZZA-ABD6.pdf Asteroids, Comets, Meteors 2014 Helsinki, Finland July 2014 2014acm..conf..559V 29 March 2025 dead https://web.archive.org/web/20150923173104/http://www.helsinki.fi/acm2014/pdf-material/Day-5/Posters-4/VERNAZZA-ABD6.pdf 23 September 2015 Patrick Michel Francesca E. DeMeo William F. Bottke Asteroids IV https://books.google.com/books?id=clnkCgAAQBAJ The Compositional Structure of the Asteroid Belt https://www.mit.edu/~fdemeo/publications/DeMeoetal2015_AIV.pdf F. E. DeMeo C. M. O'D. Alexander K. J. Walsh C. R. Chapman R. P. Binzel 2015 13–41 University of Arizona Press, Tucson 10.2458/azu_uapress_9780816532131-ch002 1506.04805 2015aste.book...13D 978-0-816-53213-1 Paolo Ulivi David M. Harland Robotic Exploration of the Solar System: Part 4: The Modern Era 2004–2013 12. The future. Main belt asteroids, Hildas, Trojans, and Centaurs. 431 Springer 2014 978-1-4614-4812-9 etal L. A. Lebofsky M. V. Sykes I. G. Nolt J. V. Radostitz G. J. Veeder D. L. Matson Submillimeter observations of the asteroid 10 Hygiea Icarus August 1985 63 2 192–200 10.1016/0019-1035(85)90003-X 1985Icar...63..192L 123477668 etal K. J. Johnston E. J. Lamphear W. J. Webster P. D. Lowman P. K. Seidelmann G. H. Kaplan The microwave spectra of the asteroids Pallas, Vesta, and Hygiea https://articles.adsabs.harvard.edu/pdf/1989AJ.....98..335J The Astronomical Journal July 1989 98 1 335–340 10.1086/115150 1989AJ.....98..335J 121508855 Thais Mothé-Diniz Mario di Martino Philippe Bendjoya Alain Doressoundiram Migliorini Fabbio Rotationally Resolved Spectra of 10 Hygiea and a Spectroscopic Study of the Hygiea Family Icarus July 2001 152 1 117–126 10.1006/icar.2001.6618 2001Icar..152..117M 120971986 etal M. A. Barucci E. Dotto J. R. Brucato T. G. Mülller P. Morris A. Doressoundiram 10 Hygiea: ISO Infrared Observations https://lesia.obspm.fr/perso/jacques-crovisier/biblio/preprint/bar02_icarus.pdf Icarus March 2002 156 1 202–210 10.1006/icar.2001.6775 2002Icar..156..202B live https://web.archive.org/web/20210227125425/https://lesia.obspm.fr/perso/jacques-crovisier/biblio/preprint/bar02_icarus.pdf 27 February 2021 Lucy F. Lim Timothy H. McConnochie James F. Bell Thomas L. Hayward Thermal infrared (8–13 μm) spectra of 29 asteroids: the Cornell Mid-Infrared Asteroid Spectroscopy (MIDAS) Survey https://molokai.sese.asu.edu/~jimbo/indexed/publications/students_postdocs/0005_Lim_L_Thermal_Infrared_Spectra_Icarus_2004.pdf Icarus 173 2 385–408 February 2005 10.1016/j.icarus.2004.08.005 2005Icar..173..385L live https://web.archive.org/web/20240810165835/https://molokai.sese.asu.edu/~jimbo/indexed/publications/students_postdocs/0005_Lim_L_Thermal_Infrared_Spectra_Icarus_2004.pdf 10 August 2024 J. E. Colwell S. Batiste, S. M. Horányi S. Robertson S. Sture Lunar surface: Dust dynamics and regolith mechanics Reviews of Geophysics June 2007 45 2 2005RG000184 RG2006 free 10.1029/2005RG000184 2007RvGeo..45.2006C 140198386 V. V. Busarev Asteroids 10 Hygiea, 135 Hertha, and 196 Philomela: Heterogeneity of the material from the reflectance spectra http://selena.sai.msu.ru/Bus/Publications/SSR-11(Busarev).pdf Solar System Research February 2011 45 1 43–52 10.1134/S0038094610061036 2011SoSyR..45...43B 123470361 live https://web.archive.org/web/20241211095635/http://selena.sai.msu.ru/Bus/Publications/SSR-11(Busarev).pdf 11 December 2024 F. E. DeMeo B. Carry The taxonomic distribution of asteroids from multi-filter all-sky photometric surveys Icarus September 2013 226 1 723–741 10.1016/j.icarus.2013.06.027 1307.2424 2013Icar..226..723D 62820731 Andrew S. Rivkin Erik Asphaug William F. Bottke The case of the missing Ceres family Icarus November 2014 243 429–439 10.1016/j.icarus.2014.08.007 2014Icar..243..429R 1650941 V. V. Busarev New reflectance spectra of 40 asteroids: A comparison with the previous results and an interpretation Solar System Research January 2016 50 1 13–23 10.1134/S0038094616010019 2016SoSyR..50...13B 255072939 etal P. Vernazza J. Castillo-Rogez P. Beck J. Emery R. Brunetto M. Delbo Different Origins or Different Evolutions? Decoding the Spectral Diversity Among C-type Asteroids The Astronomical Journal February 2017 153 2 72 72 free 10.3847/1538-3881/153/2/72 1701.06603 2017AJ....153...72V 118906259 etal J. Hanuš M. Viikinkoski F. Marchis J. Ďurech M. Kaasalainen M. Delbo' Volumes and bulk densities of forty asteroids from ADAM shape modeling Astronomy & Astrophysics May 2017 601 A114 A114 free 10.1051/0004-6361/201629956 1702.01996 2017A&A...601A.114H 119432730 Henry H. Hsieh Bojan Novaković Yoonyoung Kim Ramon Brasser Asteroid Family Associations of Active Asteroids The Astronomical Journal February 2018 155 2 96 96 free 10.3847/1538-3881/aaa5a2 1801.01152 2018AJ....155...96H 119336304 Andrew S. Rivkin Ellen S. Howell Joshua P. Emery Infrared Spectroscopy of Large, Low-Albedo Asteroids: Are Ceres and Themis Archetypes or Outliers? Journal of Geophysical Research: Planets May 2019 124 5 1393–1409 free 10.1029/2018JE005833 1904.07065 2019JGRE..124.1393R 119111853 etal M. N. De Prá N. Pinilla-Alonso J. Carvano J. Licandro D. Morate V. Lorenzi A comparative analysis of the outer-belt primitive families Astronomy & Astrophysics November 2020 643 A102 A102 free 10.1051/0004-6361/202038536 2105.11994 2020A&A...643A.102D 225280626 etal Andrew S. Rivkin Cristina A. Thomas Ian Wong Bryan Holler Helena C. Bates Ellen S. Howell Observations and Quantitative Compositional Analysis of Ceres, Pallas, and Hygiea Using JWST/NIRSpec The Planetary Science Journal January 2025 6 1 9 9 free 10.3847/PSJ/ad944c 2025PSJ.....6....9R 275535579 Fuentes-Muñoz Oscar Farnocchia Davide Giorgini Jon D. Park Ryan S. 2025-12-01 Asteroid Mass Estimation by Mutual Perturbations During Close Encounters After Gaia Focused Product Release The Astronomical Journal 170 6 353 10.3847/1538-3881/ae0cc9 0004-6256 free 2025AJ....170..353F 283347135 External links Stellar occultation by Hygiea on 11 August 2013 (video) (10) Hygiea shape model and observation details, Astronomical Institute of the Charles University 10 9 Metis 10 11 Parthenope Astronomy Stars Spaceflight Outer space Solar System Category:Hygiea asteroids Hygiea Hygiea Category:Possible dwarf planets Category:C-type asteroids (Tholen) Category:C-type asteroids (SMASS) 18490412 18490412