Surreal image of a rocky asteroid with a faint coma in the Oort Cloud

Ancient Asteroid Found in Oort Cloud: Rewriting Solar System History?

Soraya Malik in Science & Nature December 2025 • 4 min read.

"Scientists discover a rocky body lurking in the icy depths of the Oort Cloud, challenging our understanding of planet formation and solar system dynamics."

Our solar system's story is etched in the compositions of small, primitive bodies that remain from its formation. The makeup of these objects, and their current locations, reveal how material was distributed during planet formation.

Comets, traditionally icy bodies, are observed, and provide insights into the chemistry of the early solar system. These comets are like time capsules.

Now, imagine finding a rocky asteroid, similar to those in the inner solar system, way out in the Oort Cloud. That’s precisely what a team of astronomers has discovered, challenging existing models and potentially rewriting our understanding of how our solar system evolved.

C/2014 S3 (PANSTARRS): An Inner Solar System Immigrant?

Surreal image of a rocky asteroid with a faint coma in the Oort Cloud

The object, designated C/2014 S3 (PANSTARRS), has an orbit characteristic of comets originating from the Oort Cloud. What makes it stand out is its composition. Unlike the expected icy composition, C/2014 S3's spectrum closely resembles that of S-type asteroids found in the inner asteroid belt.

This S-type asteroid suggests that the material has undergone only minimal thermal processing. The spectrum indicates that the silicates—minerals like olivine and pyroxene—are similar to those found in unequilibrated ordinary chondrites (UOCs), the most primitive type of ordinary chondrites. This hints at a surface composition that closely resembles the original building blocks of the inner solar system.

Here's why this discovery is significant:

Challenging Dynamical Models: Current models for solar system formation vary in their predictions about how much rocky material from the inner regions should be present in the Oort Cloud. C/2014 S3 provides a crucial data point to test these models.
Migration Mysteries: Some models propose that giant planets significantly shifted their orbits early in solar system history, scattering material far and wide. The presence of inner solar system material in the Oort Cloud supports these migration-based models.
A 'Manx' Comet: C/2014 S3 displays a very faint level of cometary activity, far less than typical ice-rich comets. Scientists are calling this a "Manx" object, after the tailless cat, suggesting it has retained only a small fraction of the water expected from its formation location.

But how did an inner solar system asteroid end up in the Oort Cloud? According to the research team, giant planets scattering rocky material outward can explain this. C/2014 S3 represents the first step toward measuring the fraction of rocky objects in the Oort cloud and helping scientists narrow down models.

What's Next for this Oort Cloud Discovery?

The discovery of C/2014 S3 opens a window into the early solar system. It highlights that some objects underwent aqueous processing and accreted water ice close to the protoplanetary disk snowline. This research will test models, as there is the need to characterise more Manx objects.

Future research characterizing more of these "Manx" objects is crucial. Determining the abundance of S-type asteroids in the Oort Cloud will provide strong constraints for dynamical models of solar system evolution.

C/2014 S3 offers a unique opportunity to test predictions about the amount of inner solar system material residing in the Oort Cloud and to refine our understanding of the processes that shaped our planetary system. It's a tantalizing glimpse into the solar system's chaotic past and the building blocks of our own world.

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This article is based on research published under:

DOI-LINK: 10.1126/sciadv.1600038, Alternate LINK

Title: Inner Solar System Material Discovered In The Oort Cloud

Subject: Multidisciplinary

Journal: Science Advances

Publisher: American Association for the Advancement of Science (AAAS)

Authors: Karen J. Meech, Bin Yang, Jan Kleyna, Olivier R. Hainaut, Svetlana Berdyugina, Jacqueline V. Keane, Marco Micheli, Alessandro Morbidelli, Richard J. Wainscoat

Published: 2016-04-01

Everything You Need To Know

What makes C/2014 S3 (PANSTARRS) different from other comets found in the Oort Cloud?

C/2014 S3 (PANSTARRS) is unique because, unlike typical Oort Cloud comets which are icy, its spectrum resembles S-type asteroids found in the inner asteroid belt. This suggests it's a rocky object originating from the inner solar system that somehow migrated to the distant Oort Cloud, challenging traditional views of the Oort Cloud's composition and the distribution of materials during the solar system's formation.

How does the presence of C/2014 S3 (PANSTARRS) in the Oort Cloud support theories about giant planet migration?

The discovery of C/2014 S3 (PANSTARRS) supports models suggesting that the giant planets, like Jupiter and Saturn, shifted their orbits early in the solar system's history. These shifts could have scattered material from the inner solar system outward, including rocky asteroids like C/2014 S3, eventually populating the Oort Cloud with objects from diverse origins. If true, this significantly impacts our understanding of solar system dynamics and planet formation.

What is a 'Manx' comet, and what does the term imply about the composition of objects like C/2014 S3 (PANSTARRS)?

A 'Manx' comet, like C/2014 S3 (PANSTARRS), is named after the tailless Manx cat because it exhibits very little cometary activity compared to typical ice-rich comets. This suggests that it has lost most of its volatile ices, such as water, and retained only a small fraction of what was expected based on its formation location. Studying Manx comets is important for understanding the composition and evolution of comets in the Oort Cloud.

If rocky asteroids, like C/2014 S3 (PANSTARRS), are found in the Oort Cloud, what does that suggest about our current understanding of the early solar system?

The key implication is that the Oort Cloud may not be exclusively populated by icy bodies as previously thought. The discovery of C/2014 S3 (PANSTARRS) indicates that rocky material from the inner solar system can also be found in the Oort Cloud, thus requiring revisions of solar system formation models to account for the mechanisms by which such transport could occur. It shows planet migration was more chaotic than previously expected.

What does the composition of C/2014 S3 (PANSTARRS) tell us about the materials and conditions present during the early formation of the solar system?

The spectrum of C/2014 S3 (PANSTARRS) closely resembles that of S-type asteroids and contains silicates similar to those found in unequilibrated ordinary chondrites (UOCs). UOCs are the most primitive type of ordinary chondrites. This composition suggests it has undergone minimal thermal processing, hinting at a surface composition close to the original building blocks of the inner solar system. This provides clues about the conditions and materials present during the early stages of planet formation.