Scientists using NASA’s Pleiades supercomputer have discovered a spiral structure within the Oort Cloud, a distant shell of icy bodies at the edge of the solar system. The finding offers new insights into the cloud’s composition and organisation.
The spiral structure, formed by billions of comets in the inner Oort Cloud, spans approximately 15,000 astronomical units (AU). It is oriented perpendicular to the plane of the Milky Way and represents a long-lasting feature rather than a temporary alignment.
Researchers tracked the movement of millions of simulated cometary bodies over the solar system’s 4.5-billion-year history. The extensive computing power required for this study meant the analysis had to be conducted on a supercomputer.
The American Museum of Natural History’s visualisation team first identified the spiral while reviewing simulation data. Scientists had not previously observed such a structure within the Oort Cloud.
Most Oort Cloud comets remain undetectable due to their extreme distance from the Sun. Unlike comets from the outer Oort Cloud, which can be disturbed by passing stars and enter the inner solar system, those in the spiral remain more stable and are less likely to become visible.
Scientists hope to observe this spiral structure indirectly through upcoming surveys such as the Legacy Survey of Space and Time (LSST) at the Vera Rubin Observatory. Future studies may also use infrared data to detect thermal emissions from dust within the Oort Cloud.
The discovery reinforces the recurring presence of spirals in nature, from Saturn’s rings to galaxies. The researchers' findings have been published in a pre-peer-reviewed paper on the arXiv repository.