2 Pallas   

Convex hull model of 2 Pallas
Discovery
Discovered by:	Heinrich Wilhelm Olbers
Discovery date:	March 28, 1802
Alternative names:	none
Minor planet category:	Pallas family
Orbital characteristics
Epoch November 26, 2005 (JD 2453700.5)
Aphelion distance:	510.425 Gm (3.412 AU)
Perihelion distance:	319.143 Gm (2.133 AU)
Semi-major axis:	414.784 Gm (2.773 AU)
Eccentricity:	0.231
Orbital period:	1686.333 d (4.62 yr)
Avg. orbital speed:	17.65 km/s
Mean anomaly:	92.795°
Inclination:	34.841°
Longitude of ascending node:	173.152°
Argument of perihelion:	310.448°
Physical characteristics
Dimensions:	570×525×500 km[1][2]
Mass:	2.2×1020 kg[3][4]
Mean density:	2.8 g/cm³
Equatorial surface gravity:	0.18 m/s²
Escape velocity:	0.32 km/s
Rotation period:	0.32555 d[5]
Albedo:	0.159[7]
Temperature:	~164 K max: ~265 K (-8° C)
Spectral type:	B-type asteroid[6]
Absolute magnitude:	4.13[7]

2 Pallas (IPA: [ˈpʰæləs]), Greek Παλλάς) is an asteroid located in the asteroid belt region of the solar system and was the second to be discovered. It was found and named by astronomer Heinrich Wilhelm Matthäus Olbers on March 28, 1802. Image File history File links Pallas_symbol. ... Convex hull: elastic band analogy In mathematics, the convex hull or convex envelope for a set of points X in a real vector space V is the minimal convex set containing X. (Note that X may be the union of any set of objects made of points). ... Categories: Astronomers stubs | 1758 births | 1840 deaths | German astronomers | German physicists | Lists of asteroids ... March 28 is the 87th day of the year in the Gregorian Calendar (88th in leap years). ... --69. ... Provisional designation of in astronomy is the naming convention applied to astronomical objects immediately following their discovery. ... The Pallas family of asteroids is a grouping of B-type asteroids at very high inclinations in the intermediate main belt (Cellino et al (2002)). The namesake is 2 Pallas, an extremely large asteroid with a mean diameter of about 530 km. ... Two bodies with a slight difference in mass orbiting around a common barycenter. ... In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... November 26 is the 330th day (331st on leap years) of the year in the Gregorian calendar. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... The Julian day or Julian day number (JDN) is the (integer) number of days that have elapsed since Monday, January 1, 4713 BC in the proleptic Julian calendar [1]. That day is counted as Julian day zero. ... A diagram of Keplerian orbital elements. ... A diagram of Keplerian orbital elements. ... The semi-major axis of an ellipse In geometry, the term semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae. ... Look up giga- in Wiktionary, the free dictionary. ... The metre, or meter (U.S.), is a measure of length. ... The astronomical unit (AU or au or a. ... (This page refers to eccitricity in astrodynamics. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ... Water, Rabbit, and Deer: three of the 20 day symbols in the Aztec calendar, from the Aztec Sun Stone. ... In astronomy, a Julian year is a unit of time defined as exactly 365. ... The orbital speed of a body, generally a planet, a natural satellite, an artificial satellite, or a multiple star, is the speed at which it orbits around the barycenter of a system, usually around a more massive body. ... Look up second in Wiktionary, the free dictionary. ... In the study of orbital dynamics the mean anomaly is a measure of time, specific to the orbiting body p, which is a multiple of 2π radians at and only at periapsis. ... Inclination in general is the angle between a reference plane and another plane or axis of direction. ... A degree (in full, a degree of arc, arc degree, or arcdegree), usually symbolized °, is a measurement of plane angle, representing 1／360 of a full rotation. ... The Longitude of the ascending node () is one of the orbital elements used to specify the orbit of an object in space. ... The argument of periapsis (ω) is the orbital element describing the angle between an orbiting bodys ascending node (the point where the body crosses the plane of reference from South to North) and its periapsis (the point of closest approach to the central body), measured in the orbital plane and... Unsolved problems in physics: What causes anything to have mass? The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. Mass is the property of a physical object that quantifies the amount of matter and energy it is equivalent to. ... The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. It was assigned to the United States in 1889 and is periodically recertified and traceable to the primary international standard, The Kilogram, held at the Bureau International des Poids et... In physics, density is defined as mass m per unit volume V. Mathematically, it is expressed as where, in SI units: ρ (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg V is the volume of the substance... Centi (symbol c) is a SI prefix in the SI system of units denoting a factor of 10-2, or 1/100. ... The cubic meter (symbol m³) is the SI derived unit of volume. ... The surface gravity of a Killing horizon is the acceleration, as exerted at infinity, needed to keep an object at the horizon. ... Space Shuttle Atlantis launches on mission STS-71 In physics, for a given gravitational field and a given position, the escape velocity is the minimum speed an object without propulsion, at that position, needs to have to move away indefinitely from the source of the field, as opposed to falling... In astronomy, a rotation period is the time an astronomical object takes to complete one revolution around its rotation axis. ... Albedo is a ratio of scattered to incident electromagnetic radiation power. ... Fig. ... The Kelvin scale is a thermodynamic (absolute) temperature scale where absolute zero—the lowest possible temperature where nothing could be colder and no heat energy remains in a substance—is defined as zero kelvin (0 K). ... Celsius is, or relates to, the Celsius temperature scale (previously known as the centigrade scale). ... B-type asteroids are a relatively uncommon type of carbonaceous asteroid, falling into the wider C-group. ... In astronomy, absolute magnitude is the apparent magnitude, m, an object would have if it were at a standard luminosity distance away from us, in the absence of interstellar extinction. ... For information on how to read IPA transcriptions of English words see here. ... 253 Mathilde, a C-type asteroid. ... For details on the physical properties of bodies in the asteroid belt see Asteroid and Main-belt comet. ... Major features of the Solar System (not to scale, from left to right): Pluto, Neptune, Uranus, Saturn, Jupiter, the asteroid belt, the Sun, Mercury, Venus, Earth & Moon, and Mars. ... Heinrich Wilhelm Olbers. ... March 28 is the 87th day of the year in the Gregorian Calendar (88th in leap years). ... --69. ...

Pallas is the third most massive object in the asteroid belt and is estimated to contain 7% of the region's entire mass.^[3] Pallas, as well as Ceres, 3 Juno and 4 Vesta, were once considered planets until the discovery of many other asteroids led to re-classifications. It is possible that Pallas may be classified as a dwarf planet in the future, but only if it is found that its shape is consistent with hydrostatic equilibrium.^[8] Spectral type: G Absolute magnitude: 3. ... 3 Juno (jew-noe (key)) was the third asteroid to be discovered and is one of the largest main belt asteroids, being the heaviest of the stony S-type. ... 4 Vesta (ves-ta) is the second most massive asteroid in the asteroid belt, with a mean diameter of about 530 km and an estimated mass 12% the mass of the entire asteroid belt. ... Artists impression of Pluto (background) and Charon (foreground). ... Hydrostatic equilibrium occurs when compression due to gravity is balanced by a pressure gradient which creates a pressure gradient force in the opposite direction. ...

Name

The asteroid is named after Pallas, the daughter of Triton and friend of Athena in Greek mythology. The name also refers to Pallas Athena (Παλλάς Αθηνά), a title the goddess Athena attained after supplanting Pallas. (In some mythologies Athena killed Pallas, then adopted her friend's name out of mourning.) There are several male characters of the same name in Greek mythology, but the first asteroids were invariably given female names. Pallas Athena. ... Triton is a Greek god, the messenger of the deep. ... Helmeted Athena, of the Velletri type. ... The bust of Zeus found at Otricoli (Sala Rotonda, Museo Pio-Clementino, Vatican) Greek mythology is the body of stories belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world and their own cult and ritual practices. ...

According to the OED, the adjectival form of Pallas is Palladian. Pallas' astronomical and astrological symbol is or sometimes    . The Oxford English Dictionary print set The Oxford English Dictionary (OED) is a dictionary published by the Oxford University Press (OUP), and is generally regarded as the most comprehensive and scholarly dictionary of the English language. ... Image File history File links Pallas_symbol. ... Image File history File links 2_Pallas_(1). ...

The chemical element palladium (atomic number 46) was named after Pallas. General Name, Symbol, Number palladium, Pd, 46 Chemical series transition metals Group, Period, Block 10, 5, d Appearance silvery white metallic Atomic mass 106. ...

History of observation

In 1801, the astronomer Giuseppe Piazzi discovered an object which he initially believed to be a comet. Shortly thereafter he announced his observations of this object, noting that the slow, uniform motion that were uncharacteristic of a comet, suggesting it was a different type of object. This was lost from sight for several months, but was recovered later in the year by the Baron von Zach and Heinrich W. M. Olbers after a preliminary orbit was computed by Friedrich Gauss. This object came to be named Ceres, and was the first asteroid to be discovered. Giuseppe Piazzi. ... Comet Hale-Bopp Comet McNaught as seen from Swifts Creek, Victoria, Australia on 23 January 2007 A comet is a small body in the solar system that orbits the Sun and (at least occasionally) exhibits a coma (or atmosphere) and/or a tail â€” both primarily from the effects of... Franz Xaver, Baron Von Zach Baron Franz Xaver von Zach (Franz Xaver Freiherr von Zach) (June 4, 1754 - September 2, 1832) was an Austrian astronomer born at Bratislava. ... Heinrich Wilhelm Olbers. ...   (30 April 1777 – 23 February 1855) was a German mathematician and scientist of profound genius who contributed significantly to many fields, including number theory, analysis, differential geometry, geodesy, magnetism, astronomy and optics. ... Spectral type: G Absolute magnitude: 3. ...

A few months later, Olbers was again attempting to locate Ceres when he noticed another moving object in the vicinity. This was the asteroid Pallas, coincidentally passing near Ceres at the time. The discovery of this object created interest in the astronomy community. Prior to this point it had been speculated by astronomers that there should be a planet in the gap between Mars and Jupiter. Now, unexpectedly, a second such body had been found.^[9] Mars is the fourth planet from the Sun in the solar system, named after the Roman god of war (the counterpart of the Greek Ares), on account of its blood red color as viewed in the night sky. ... Adjectives: Jovian Atmosphere Surface pressure: 20–200 kPa[4] (cloud layer) Composition: ~86% H2 ~13% Helium 0. ...

The orbit of Pallas was determined by Gauss, who found the period of 4.6 years was similar to the period for Ceres. However, Pallas had a relatively high orbital inclination to the plane of the ecliptic.^[9] Inclination in general is the angle between a reference plane and another plane or axis of direction. ... The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ...

In 1917, the Japanese astronomer Kiyotsugu Hirayama began to study asteroid motions. By plotting a set of asteroids based on their mean orbital motion, inclination and eccentricty, he discovered several distinct groupings. In a later paper he reported a group of three asteroids associated with Pallas, which became named the Pallas family after the largest member of the group.^[10] Since 1994 more than 10 members of this family have been identified. (Members have semi-major axis = 2.50–2.82 AU; inclination = 33–38°.)^[11] The existence of this family was finally confirmed in 2002 by a comparison of their spectra.^[12] Kiyotsugu Hirayama (平山清次) (1874–1943) was a Japanese astronomer, best known for his discovery that many asteroid orbits were more similar to one another than chance would allow, leading to the concept of asteroid families, now called Hirayama families in his honour. ... The Pallas family of asteroids is a grouping of B-type asteroids at very high inclinations in the intermediate main belt (Cellino et al (2002)). The namesake is 2 Pallas, an extremely large asteroid with a mean diameter of about 530 km. ...

Pallas has been observed occulting a star several times, including the best observed of all asteroid occultation events on May 29, 1983, when careful occultation timing measurements were taken by 140 observers. These have helped determine an accurate diameter.^[1][2] During the occultation of May 29, 1979 the discovery of a possible tiny satellite with a diameter of ~1 km was reported. However, it has not been confirmed. In 1980, speckle interferometry was reported as indicating a much larger satellite with a diameter of 175 km, but the existence of the satellite was later refuted.^[13] In this July, 1997 still frame captured from video, the bright star Aldebaran has just reappeared on the dark limb of the waning crescent moon in this predawn occultation. ... This article is about the astronomical object. ... May 29 is the 149th day of the year in the Gregorian calendar (150th in leap years). ... 1983 (MCMLXXXIII) was a common year starting on Saturday of the Gregorian calendar. ... May 29 is the 149th day of the year in the Gregorian calendar (150th in leap years). ... For the song by The Smashing Pumpkins, see 1979 (song). ... Moons of the Solar System scaled to Earths Moon A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... 1980 (MCMLXXX) was a leap year starting on Tuesday. ... Speckle interferometry is an image processing technique used in astronomy that can dramatically increase the resolution of ground-based telescopes. ...

Radio signals from spacecraft in orbit around Mars and/or on its surface have been used to estimate the mass of Pallas from the tiny perturbations induced by it onto the motion of Mars.^[3] Note: This article contains special characters. ... Note: This article contains special characters. ...

There have not been any telescopic observations of Pallas that have resolved any features on its disk. Pallas has not yet been visited by a spacecraft, but if the Dawn probe is successful in studying 1 Ceres and 4 Vesta, its mission may be extended to Pallas. Due to the high orbital inclination of Pallas, it is more difficult for a spacecraft to reach than the other large asteroids.^[14] The Dawn Mission is a NASA unmanned space mission currently under development to send an orbiting space probe to examine the two most massive members of the asteroid belt, the dwarf planet Ceres and the asteroid Vesta. ... 1 Ceres (IPA , Latin: ) is a dwarf planet in the asteroid belt. ... 4 Vesta (ves-ta) is the second most massive asteroid in the asteroid belt, with a mean diameter of about 530 km and an estimated mass 12% the mass of the entire asteroid belt. ...

Characteristics

Size comparison: the first 10 asteroids profiled against Earth's Moon. Pallas is at second left.

Pallas is the third largest object in the asteroid belt, similar to 4 Vesta in volume (to within uncertainty), but somewhat less massive. By comparison, the mass of Pallas is only about 0.3% of the Moon's mass. Both Pallas and Vesta have assumed the title of second largest asteroid from time to time.^[14] However, Vesta has a much higher albedo than Pallas, and consequently appears brighter on average. Image File history File links The first 10 asteroids profiled against the Earths Moon. ... Image File history File links The first 10 asteroids profiled against the Earths Moon. ... Apparent magnitude: up to -12. ... 4 Vesta (ves-ta) is the second most massive asteroid in the asteroid belt, with a mean diameter of about 530 km and an estimated mass 12% the mass of the entire asteroid belt. ... Apparent magnitude: up to -12. ...

It remains uncertain whether Pallas is in hydrostatic equilibrium. That is, whether it is sufficiently massive to have overcome its own rigidity and assume a more spheroidal form. If it has achieved this form of equilibrium, Pallas may qualify as a dwarf planet.^[8] Hydrostatic equilibrium occurs when compression due to gravity is balanced by a pressure gradient which creates a pressure gradient force in the opposite direction. ...

There is some consideration that the largest asteroids, such as Pallas, are actually protoplanets. During the planetary formation stage of the solar system, objects grew in size through an accretion process. Many of the objects the size of Ceres and Pallas were accreted by the largest bodies, which became the planets. Other protoplanetary bodies were destroyed through collisions with similar-size bodies. Pallas is likely a survivor of this early planetary-formation phase.^[15] In cosmogony, a protoplanet is a quasi-planetoid which is slightly larger than a planetesimal and orbits within a solar nebulas protoplanetary discs. ... Major features of the Solar System (not to scale, from left to right): Pluto, Neptune, Uranus, Saturn, Jupiter, the asteroid belt, the Sun, Mercury, Venus, Earth & Moon, and Mars. ... In astrophysics, the term accretion is used for at least two distinct processes. ... The eight planets and three dwarf planets of the Solar System. ...

Pallas has unusual dynamical parameters for such a large body. Its orbit is highly inclined and somewhat eccentric despite being located at the same distance from the sun as the central part of the main belt. Furthermore, its axial tilt is very high, being around 60° (in fact estimates vary from 56° to 81°).^[1][16][17] This means that, every palladian summer and winter, large parts of the surface are in constant sunlight or constant darkness for a time of the order of an Earth year. In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ... Inclination in general is the angle between a reference plane and another plane or axis of direction. ... In astrodynamics, under standard assumptions any orbit must be of conic section shape. ... The asteroid belt is a region of the solar system falling roughly between the planets Mars and Jupiter where the greatest concentration of asteroid orbits can be found. ... Axial tilt is an astronomical term regarding the inclination angle of a planets rotational axis in relation to its orbital plane. ... Adjectives: Terrestrial, Terran, Telluric, Tellurian, Earthly Atmosphere Surface pressure: 101. ...

Consensus has not been reached as to whether Pallas' rotation is prograde or retrograde. The most recent analysis of lightcurves indicates that the pole points towards ecliptic coordinates (β, λ) = (-12°, 35°) or (43°, 193°) with a 10° uncertainty.^[17] This gives axial tilts of 57° or 65°, respectively. Prograde motion is the motion of a planetary body in a direction similar to that of other bodies within its system, and is sometimes called direct motion, especially in astrology. ... The ecliptic coordinate system is a celestial coordinate system that uses the ecliptic for its fundamental plane. ... Axial tilt is an astronomical term regarding the inclination angle of a planets rotational axis in relation to its orbital plane. ...

Based on spectroscopic observations, the primary component of the Pallas surface material is a silicate that is low in iron and water. Minerals of this type include olivine and pyroxene, which are found in CM chondrules.^[18] There are indications that the surface composition of Pallas is very similar to the Renazzo carbonaceous chondrite (CR) meteorites, which is even lower in hydrous minerals than the CM type.^[19] The Renazzo meteorite was discovered in Italy in 1824, and is one of the most primitive meteorites known.^[20] The mineral olivine (also called chrysolite and, when gem-quality, peridot) is a magnesium iron silicate with the formula (Mg,Fe)2SiO4. ... Figure 1:Mantle-peridotite xenolith with green peridot olivine and black pyroxene crystals from San Carlos Indian Reservation, Gila Co. ... Chondrules in the chondrite Grassland. ... Some carbonaceous chondrites. ...

Note that the stony-iron Pallasite meteorites do not originate from the Pallas asteroid, being instead named after the German naturalist Peter S. Pallas. A pallasite is a stony-iron meteorite. ... Peter Simon Pallas (September 22, 1741 - September 8, 1811) was a German-born Russian zoologist. ...

See also

• Pallas in fiction
• List of Solar System bodies formerly considered planets

Asteroids have become a common theme in science fiction. ... The following is a list of solar system bodies formerly considered planets: 1 Ceres 3 Juno Moon 2 Pallas Sun 4 Vesta The Galilean Moons of Jupiter (called the Medicean Planets by their discoverer, Galileo Galilei) Some astronomers now consider Pluto to be a minor planet, though this is disputed. ...

References

2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini (common) era. ... March 15 is the 74th day of the year in the Gregorian Calendar (75th in leap years). ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini (common) era. ... For the Lebanese political coalition, see March 14 Alliance. ... Elena Vladimirovna Pitjeva is a Russian theoretical physicist at the Institute of Applied Astronomy, Russian Academy of Sciences, St. ... The Eiffel Tower has become the symbol of Paris throughout the world. ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini (common) era. ... March 15 is the 74th day of the year in the Gregorian Calendar (75th in leap years). ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini (common) era. ... March 15 is the 74th day of the year in the Gregorian Calendar (75th in leap years). ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini (common) era. ... March 15 is the 74th day of the year in the Gregorian Calendar (75th in leap years). ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini (common) era. ... March 15 is the 74th day of the year in the Gregorian Calendar (75th in leap years). ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini (common) era. ... March 17 is the 76th day of the year in the Gregorian Calendar (77th in leap years). ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini (common) era. ... March 15 is the 74th day of the year in the Gregorian Calendar (75th in leap years). ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini (common) era. ... January 8 is the 8th day of the year in the Gregorian calendar. ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini (common) era. ... March 15 is the 74th day of the year in the Gregorian Calendar (75th in leap years). ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini (common) era. ... March 15 is the 74th day of the year in the Gregorian Calendar (75th in leap years). ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini (common) era. ... For the Lebanese political coalition, see March 14 Alliance. ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini (common) era. ... March 17 is the 76th day of the year in the Gregorian Calendar (77th in leap years). ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini (common) era. ... March 19 is the 78th day of the year in the Gregorian calendar (79th in leap years). ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini (common) era. ... March 15 is the 74th day of the year in the Gregorian Calendar (75th in leap years). ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini (common) era. ... March 15 is the 74th day of the year in the Gregorian Calendar (75th in leap years). ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini (common) era. ... March 19 is the 78th day of the year in the Gregorian calendar (79th in leap years). ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini (common) era. ... For the Lebanese political coalition, see March 14 Alliance. ... For the Manfred Mann album, see 2006 (album). ... May 24 is the 144th day of the year in the Gregorian calendar (145th in leap years). ...

External links

• Tedesco, Edward F.; Noah, Paul V.; Noah, Meg; Price, Stephan D. (2002). "The Supplemental IRAS Minor Planet Survey". The Astronomical Journal 123 (2): 1056-1085. Retrieved on 2007-03-15. 
• Hilton, James L. (April 1, 1999). U.S. Naval Observatory Ephemerides of the Largest Asteroids. U.S. Naval Observatory. Retrieved on 2007-03-14.
• Dunn, Tony (2006). Ceres, Pallas Vesta and Hygeia. GravitySimulator.com. Retrieved on 2007-03-15.
• Yeomans, Donald K.. Horizons system. NASA JPL. Retrieved on 2007-03-20. — Horizons can be used to obtain a current ephemeris.