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Young asteroids—which formed much later than those that were created during the formation of our solar system—are typically created when larger asteroids, planetesimals, or comets collide and break up into smaller pieces. These smaller pieces form "asteroid families" that share certain properties, like their semimajor axis, eccentricity, and inclination—all of which describe their orbital paths.

Scientists generally describe young asteroid families as being less than around 10–15 million years old and consisting of at least three members. New research, in the journal Icarus, just revealed 63 newly discovered young asteroid families less than around 10 million years old. While many of these young families are likely to exist in our solar system, only 43 had been previously documented. The new study used a five-dimensional Hierarchical Clustering Method (HCM) with a catalog of 1.25 million asteroid orbits, which enabled the team to bring the total number of known young asteroid families to 106.

The team searched for clustering in proper orbital elements (semimajor axis, eccentricity, inclination, nodal and perihelion longitudes) at various times in the past 10 million years to find groups with similar elements.

The research team's analysis revealed that most groups were actually less than one million years old, far less than the cap of 10 million for young asteroid families in this study. They also found that most groups consisted of only 3–10 members, although a few had many more, and the largest group had 58 members.

"It is expected that most new young families should have very few members, because these member asteroids are faint and at the limit of our current telescopic capabilities. In this sense, the identified members represent the tip of the iceberg, and many more members will probably be found in the future," the authors explain.

Although most known asteroids are carbonaceous—or C-type—in nature, the majority of these new young families were S-type asteroids, meaning they're composed of stony materials, like silicate and nickel-iron.

Interestingly, around 54% of the new families were found to be within older, established families. This occurs when one asteroid within an older family is broken up into even smaller pieces, creating a family within a family.

The study authors note that there are probably many more young asteroid families out there. They say detection is biased toward small, faint, and very young families, while the older or more dispersed families may be missed by their methods. Still, this work leads scientists a step closer to understanding the origins of meteorites and the ongoing evolution of our solar system—possibly even helping to detect potential Earth-asteroid impacts earlier.