Asteroid Pallas

Asteroid Pallas

Pallas, once considered a planet, as were all of the main asteroids in this belt, has fallen in its classification status. It's now considered an asteroid and nothing more. However, astronomers can't definitively prove that it's not a dwarf planet – it might have enough gravity to pull itself into a sphere. Its orbit and orbital eccentricity make this asteroid inaccessible to modern spacecraft, but the Dawn mission might do a flyby and try to gather as much information as it possibly can. Without closer examination it may never be elevated in status again. That doesn't mean that there is nothing interesting about this celestial body nor does it mean that there is nothing known about it.

Pallas accounts for over 7% of the total mass of the asteroid belt between Mars and Jupiter. While it rivals Vesta in size (582 km by 500 km) it is smaller in mass (2.11 x 10²⁰ kg) and comes in as the 3rd largest of the 4 major asteroids. Pallas was discovered on March 28, 1802 by Heinrich Wilhelm Olbers (he also discovered Vesta). What a great triumph that was to discover multiple objects in one career. Pallas has been observed many times, but because of its high ellipsis, modern spacecraft can't orbit the planet. The science of the future will have to determine this asteroid's fate.

It is possible that the largest asteroids, including Pallas, are protoplanets. During the planetary formation stage of the Solar System objects grew in size through a process known as accretion to be approximately the size of Pallas. Some of these objects were pulled together to become larger bodies, which became the planets while others wiped each other out. Pallas is a likely survivor from the early stages of planetary formation as are many of the dwarf planets.

Just because Pallas won't be orbited during your lifetime doesn't mean that it'll be a waste of your time to study it. You can easily see this object with a pair of 10×50 binoculars. It has a brightness magnitude of +6.4 to +10.6. It's also thought to have a small orbiting object of its own. Attempts have been made to verify this, but nothing conclusive has been found so far. Maybe you could be the one to change all of that. Perhaps you could be the one to discover the type of engine that is needed to orbit an object with the type of ellipsis the Pallas has? Why not? The sky is the limit with astronomy and education.

We've written many articles about Pallas for Universe Today. Here's an article about a Weekly Skywatcher guide that helps you find Pallas. And here's an article about a rare meteorite that was discovered.

Want more resources on asteroids? Here's NASA's Lunar and Planetary Science Page on asteroids. And here's NASA's World Book on Asteroids.

We have recorded two episodes of Astronomy Cast about asteroids. There's Episode 55: The Asteroid Belt, and here's Episode 29: Asteroids Make Bad Neighbors.

Filed under: Astronomy