2 Pallas

Pallas is a very large rock in space.

It is the third largest rock in its group. It is very old. It was made a long time ago.

A man found it in the year 1802. He thought it was a planet. Today we call it an asteroid. It has many big holes on its surface. These holes were made by rocks hitting it. It is a very special part of our space.

Pallas is a very large asteroid in our Solar System.

It is the third largest by mass and volume. A man named Heinrich Olbers found it in 1802. At that time, people thought it was a planet.

Today, we call it an asteroid or a planetoid.

Pallas is a leftover piece from when planets formed. Scientists think it is a protoplanet. This means it was a large object that almost became a planet. Most objects like this grew into big planets. Others were destroyed by hits from other rocks. Pallas survived.

Its path through space is very unusual. It has a high orbital inclination. This means its path is tilted sharply. Because of this tilt, it is hard for spacecraft to reach.

The surface of Pallas is covered in craters. These are large holes made by impacts. Some holes are more than 40 km wide. These hits happen with much more power than on other asteroids. This is because Pallas moves very fast through space.

Pallas is a huge object in our Solar System.

It is the third-largest asteroid by both volume and mass. Scientists believe it is a remnant protoplanet. A protoplanet is a large object that almost became a planet. During the early days of our Solar System, objects grew through a process called accretion. Most of these objects grew into the large planets we know today. Others were destroyed by collisions or pushed away by big planets. Pallas is one of the few intact bodies from that early time.

Finding Pallas was a big moment for astronomers. The German astronomer Heinrich Wilhelm Matthias Olbers discovered it on 28 March 1802. At that time, people actually thought it was a planet. This was because many other asteroids were also called planets back then. After 1845, more asteroids were found, so scientists changed the names. They started calling these smaller bodies asteroids or planetoids.

The name Pallas comes from a Greek goddess. This name was chosen because it is an epithet for Athena.

Its path through space is very unusual. Pallas has a high orbital inclination. This means its path is tilted sharply compared to the rest of the asteroid belt. This tilt makes it hard for spacecraft to reach.

It also has a high orbital eccentricity. This means its path is not a perfect circle. Because of this tilt, Pallas can pass very close to certain stars. For example, it passed near the star Sirius on 9 October 2022. No regular planet can get that close to Sirius.

The surface of Pallas is very rough. It is covered in many craters from space rocks hitting it. These impacts are much more energetic than hits on other asteroids. This happens because Pallas moves with much higher velocity. Some craters are larger than 40 km across. These large holes cover at least 9% of its surface.

There is even a possible large impact basin at the south pole. This hit might have been big enough to eject a huge amount of material.

We can learn about Pallas by looking at its makeup. Its surface is mostly made of silicate material. This is a type of rock that contains little iron or water. The minerals on Pallas are similar to carbonaceous chondrite meteorites. These are rocks that fell to Earth from space. Pallas is also part of the Pallas family of asteroids. This is a group of asteroids that share similar paths. Scientists confirmed this group exists by comparing their spectra, which is a way to study light.

2 Pallas is the third-largest asteroid in our Solar System by mass and volume.

It is considered a remnant protoplanet. A protoplanet is a large object that formed during the early stages of the Solar System. During this era, objects grew through a process called accretion. In accretion, small particles clump together to form larger bodies. Most protoplanets eventually became the major planets we know today. Others were destroyed by collisions or ejected by the gravity of larger planets. Pallas, along with Ceres and Vesta, is one of the few intact bodies from this early era surviving within the orbit of Neptune.

The composition of Pallas provides clues about the early Solar System. It is a B-type asteroid, meaning its surface is mostly silicate material. This material contains very little iron or water. Its minerals, such as olivine and pyroxene, are similar to carbonaceous chondrite meteorites. Specifically, its surface is very similar to Renazzo carbonaceous chondrite meteorites. These are some of the most primitive meteorites known. While Pallas has a mineral composition similar to Ceres, it is significantly less hydrated. This means it contains less water within its minerals than Ceres does.

Pallas has very unusual orbital characteristics. It has a high orbital inclination of 34.8 degrees. This means its path is tilted sharply relative to the plane of the asteroid belt. This tilt makes Pallas difficult for spacecraft to reach. It also has a high orbital eccentricity, which means its orbit is not a perfect circle. In fact, its eccentricity is nearly as large as that of Pluto. Because of this high inclination, Pallas can pass very close to stars that other solar objects avoid. On 9 October 2022, Pallas passed near the star Sirius. It passed only 8.5 arcminutes south of the star. No regular planet can get closer than 30 degrees to Sirius.

The history of Pallas involves several important astronomers. Charles Messier recorded Pallas on a star chart in 1779, but he thought it was a star. In 1801, Giuseppe Piazzi discovered Ceres, the first asteroid. A few months later, Heinrich Wilhelm Matthias Olbers discovered Pallas while searching for Ceres. At the time, astronomers believed a planet existed in the gap between Mars and Jupiter. The discovery of both Ceres and Pallas supported this idea. In the early 19th century, Pallas was actually classified as a planet. It was only after more asteroids were found after 1845 that scientists began using the term "minor planet." Later, in the 1950s, the term "asteroid" became more common.

The name Pallas is an epithet for the Greek goddess Athena. In some myths, Athena accidentally killed a girl named Pallas. Out of mourning, the goddess adopted her friend's name. The asteroid's name is also linked to the chemical element palladium. The element was named after the asteroid because it was discovered shortly after the object was found. The old astronomical symbol for Pallas is a spear or lance. This symbol is still used in astrology today.

The physical surface of Pallas is heavily impacted. It appears to be saturated with craters. Because of its high inclination and eccentricity, impacts on Pallas are very energetic. These impacts occur at twice the velocity of hits on Vesta or Ceres. This high speed allows smaller objects to create large craters. Craters larger than 40 km in diameter cover at least 9% of its surface.

There is a possible large impact basin at the south pole. This impact may have ejected a volume of material equal to the size of Pallas. This event might have caused the asteroid's high inclination and slowed its rotation.

Pallas is also part of a larger group called the Pallas family. In 1917, the astronomer Kiyotsugu Hirayama began studying asteroid motions. He discovered that certain asteroids move in distinct groupings. He identified a group of three asteroids associated with Pallas. Since 1994, scientists have identified more than 10 members of this family. These members have inclinations between 33 and 38 degrees. The existence of this family was confirmed in 2002 through spectral comparisons.