Pallas (minor-planet designation: 2 Pallas) is the second asteroid to have been discovered, after Ceres. It is believed to have a mineral composition similar to carbonaceous chondrite meteorites, like Ceres, though significantly less hydrated than Ceres. It is the third-largest asteroid in the Solar System by both volume and mass, and is a likely remnant protoplanet. It is 79% the mass of Vesta and 22% the mass of Ceres, constituting an estimated 7% of the mass of the asteroid belt. Its estimated volume is equivalent to a sphere 507 to 515 kilometers (315 to 320 mi) in diameter, 9095% the volume of Vesta.
During the planetary formation era of the Solar System, objects grew in size through an accretion process to approximately the size of Pallas. Most of these protoplanets were incorporated into the growth of larger bodies, which became the planets, whereas others were ejected by the planets or destroyed in collisions with each other. Pallas, Vesta and Ceres appear to be the only intact bodies from this early stage of planetary formation to survive within the orbit of Neptune.When Pallas was discovered by the German astronomer Heinrich Wilhelm Matthus Olbers on 28 March 1802, it was considered to be a planet, as were other asteroids in the early 19th century. The discovery of many more asteroids after 1845 eventually led to the separate listing of "minor" planets from "major" planets, and the realization in the 1950s that such small bodies did not form in the same way as (other) planets led to the gradual abandonment of the term "minor planet" in favor of "asteroid" (or, for larger bodies such as Pallas, "planetoid").
With an orbital inclination of 34.8, Pallas's orbit is unusually highly inclined to the plane of the asteroid belt, making Pallas relatively inaccessible to spacecraft, and its orbital eccentricity is nearly as large as that of Pluto.
Heinrich Wilhelm Matthias Olbers (; German: [ˈɔlbɐs]; 11 October 1758 – 2 March 1840) was a German physician and astronomer.
1802Mar, 28
Heinrich Wilhelm Matthäus Olbers discovers 2 Pallas, the second asteroid ever to be discovered.
Choose Another Date
Events on 1802
- 28Mar
2 Pallas
Heinrich Wilhelm Matthäus Olbers discovers 2 Pallas, the second asteroid ever to be discovered. - 21Apr
Wahhabi sack of Karbala
Twelve thousand Wahhabis under Abdul-Aziz bin Muhammad, invaded city of Karbala, killed over three thousand inhabitants, and sacked the city. - 28May
Louis Delgrès
In Guadeloupe, 400 rebellious slaves, led by Louis Delgrès, blow themselves up rather than submit to Napoleon's troops - 4Jul
United States Military Academy
At West Point, New York, the United States Military Academy opens. - 3Sep
Composed upon Westminster Bridge, September 3, 1802
William Wordsworth composes the sonnet Composed upon Westminster Bridge, September 3, 1802.