Pallas
Key facts
- What it is
- Large main-belt asteroid
- Size
- About 510 km across
- Discovered
- 1802, by Heinrich Olbers
- Spacecraft
- Not yet visited
- Orbit group
- Main-belt Asteroid
- Average distance from the Sun
- 2.77 au (about 410 million km)
- Time to go round the Sun
- 4.6 years
- Closest and farthest from the Sun
- 2.13 to 3.41 au
- Tilt of its orbit
- 34.9°
- Spins once every
- 7.8 hours
An au (astronomical unit) is Earth's average distance from the Sun, about 150 million km. Orbit figures are from open tracking data, figures last updated 1 Nov 2026.
Pallas was the second asteroid discovered, found by the German physician and astronomer Heinrich Olbers in March 1802 while he was following Ceres. At about 510 kilometres across, it is one of the three largest bodies in the main belt.
What sets Pallas apart is its orbit. It is tilted by about 35 degrees to the plane in which the planets move, far more steeply than most large asteroids. Because of that tilt, Pallas crashes through the belt at an angle, so collisions with other asteroids happen at higher speeds than usual. Detailed images taken with large ground-based telescopes show a surface pitted with large craters, which fits that violent history. Its unusual orbit also makes Pallas very hard to reach: a spacecraft would need a great deal of fuel to match its path, which is one reason no mission has yet been sent.
Pallas reflects light in a way that places it among the B-type asteroids, a fairly rare group related to the dark, carbon-rich C types. Its surface seems to contain water-altered minerals, so like Ceres it probably formed with ice in its make-up. A group of smaller asteroids on similar tilted orbits, the Pallas family, are thought to be fragments knocked off it by an ancient impact.
Pallas also gave its name to a chemical element. Palladium, discovered by William Hyde Wollaston in 1802, was named after this newly found asteroid, which shows how exciting these first discoveries seemed at the time.