Karin, Koronis and Massalia

Recently, a team studied the composition of meteorites found on Earth and conducted a telescopic survey of the materials that make up the major asteroid families in the asteroid belt.

• An asteroid family “is a group of asteroids which have similar orbits because they were fragments created during a collision between two asteroids,” within the asteroid belt.

• The three major asteroid families identified in the studies are called Karin, Koronis and Massalia.

• They formed as a result of three collisions 5.8 million, 7.5 million and about 40 million years ago, respectively.

• Those are recent origins, compared to the overall age of our solar system, which is about 4.6 billion years old.

• Researchers found that the Karin and Koronis families account for a type of meteorites called H chondrites, which make up 33 percent of Earth’s known meteorites, per Reuters.

• The Massalia family, on the other hand, is responsible for a type of meteorite called L chondrites, which make up 37 percent of Earth’s meteorites.

Chondrites

• Each year, roughly 17,000 of fireballs not only enter Earth’s atmosphere, but survive the perilous journey to the surface.

• While some of these meteorites come from the Moon and Mars, the majority come from asteroids.

• Only when a fireball reaches Earth’s surface is it called a meteorite.

• They are commonly designated as three types: stony meteorites, iron meteorites, and stony-iron meteorites.

• The most common are the chondrites, which have round objects inside that appear to have formed as melt droplets. These comprise 85% of all meteorites found on Earth. Most are known as “ordinary chondrites”.

• They are then divided into three broad classes – H, L and LL – based on the iron content of the meteorites and the distribution of iron and magnesium in the major minerals olivine and pyroxene.

• These silicate minerals are the mineral building blocks of our Solar System and are common on Earth, being present in basalt. “Carbonaceous chondrites” are a distinct group.

• They contain high amounts of water in clay minerals, and organic materials such as amino acids.

• Chondrites have never been melted and are direct samples of the dust that originally formed the solar system.

• The less common of the two types of stony meteorites are the so-called “achondrites”.

• Asteroids are the primary sources of meteorites. Most asteroids reside in a dense belt between Mars and Jupiter.

• The asteroid belt itself consists of millions of asteroids swept around and marshalled by the gravitational force of Jupiter.