2 Pallas

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2 Pallas
Discovery A (http://cfa-www.harvard.edu/iau/lists/NumberedMPs.html)
Discoverer Heinrich Wilhelm Olbers
Discovery date March 28, 1802
  B (http://cfa-www.harvard.edu/iau/MPDes.html)
Category Main belt
Orbital elements C (http://asteroid.lowell.edu/)
Epoch July 14, 2004 (JD 2453200.5)
Eccentricity (e) 0.230
Semi-major axis (a) 414.717 Gm (2.772 AU)
Perihelion (q) 319.358 Gm (2.135 AU)
Aphelion (Q) 510.077 Gm (3.410 AU)
Orbital period (P) 1685.927 d (4.62 a)
Mean orbital speed 17.89 km/s
Inclination (i) 34.852
Longitude of the
ascending node
Argument of
Mean anomaly (M) 346.022
Physical characteristics
Dimensions 570×525×482 km
Mass 2.061020 kg
Density 4.2 g/cm
Surface gravity 0.16 m/s
Escape velocity 0.35 km/s
Rotation period 0.32555 d
Spectral class U
Absolute magnitude 4.13
Albedo 0.159
Mean surface
~165 K

2 Pallas (pal'-us) was the first asteroid discovered after 1 Ceres. It was found and named by H. Wilhelm Olbers on March 28, 1802. It was named after the feminine Pallas of Greek mythology, the daughter of Triton and friend of Athena. There are several other Pallantes (the masculine plural of Pallas) in Greek mythology: amongst them a Titan, and a goatish Giant. However, the first asteroids were invariably given female names.

Pallas is the second largest Main belt asteroid, only a little larger than 4 Vesta. Its orbit is located in the central part of the belt but it is somewhat inclined and eccentric for a large asteroid. The Palladian composition is unique but quite similar to the C-type asteroids.

Pallas has been observed occulting a star several times. Careful occultation timing measurements have helped give it an accurate diameter.

Missing image
The four largest asteroids. Top: 1 Ceres and 2 Pallas. Bottom: 4 Vesta and 10 Hygiea

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. (1) (http://www.johnstonsarchive.net/astro/asteroidmoonsq.html)

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.

The chemical element palladium (atomic number 46) was named after Pallas.


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The minor planets
Vulcanoids | Main belt | Groups and families | Near-Earth objects | Jupiter Trojans
Centaurs | Trans-Neptunians | Damocloids | Comets | Kuiper belt | Oort cloud
(For other objects and regions, see: Binary asteroids, Asteroid moons and the Solar system)
(For a complete listing, see: List of asteroids. For pronunciation, see: Pronunciation of asteroid names.)
bg:2 Палада

de:Pallas (Asteroid) es:(2) Palas fr:2 Pallas ja:パラス (小惑星) pl:Pallas (astronomia) pt:2 Pallas


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