Our solar system is teeming with celestial bodies, including a vast array of moons orbiting planets like Saturn. Astronomers also believe that planets outside our solar system, known as exoplanets, likely harbor their own moons, called exomoons. While exomoons remain elusive, a new breed of moons has captured the attention of researchers: those orbiting asteroids.
It may seem surprising, but asteroids often have their own tiny moons, forming what are called binary asteroids. A prime example is the famous pair Didymos and Dimorphos, the target of NASA’s DART mission in 2022. Now, thanks to data from the European Space Agency’s Gaia mission, a space-based telescope mapping the Milky Way in 3D, astronomers have identified hundreds of potential new asteroid moons.
“Binary asteroids are difficult to find as they are mostly so small and far away from us,” explained lead researcher Luana Liberato of Observatoire de la Côte d’Azur, France. “Despite us expecting just under one-sixth of asteroids to have a companion, so far we have only found 500 of the million known asteroids to be in binary systems. But this discovery shows that there are many asteroid moons out there just waiting to be found.”
Gaia’s meticulous observations have yielded a wealth of data about objects within our solar system. This data has revealed the presence of numerous potential asteroid binaries, which could nearly double the known count. Gaia identifies these binaries by detecting a telltale “wobble” in the orbits of larger asteroids, signifying the gravitational influence of a smaller companion.
Gaia’s data collection continues, and a major data release scheduled for 2026 promises to unveil even more asteroid orbits. “Gaia has proven to be an outstanding asteroid explorer, and is hard at work revealing the secrets of the cosmos both within and beyond the Solar System,” remarked Timo Prusti, project scientist for Gaia at ESA. “This finding highlights how each Gaia data release is a major step up in data quality, and demonstrates the amazing new science made possible by the mission.” The research findings have been published in the esteemed journal Astronomy & Astrophysics.
This groundbreaking discovery underscores the power of advanced space missions like Gaia in unraveling the mysteries of our celestial neighborhood. With each new data release, Gaia continues to push the boundaries of our understanding, revealing a universe teeming with fascinating celestial objects waiting to be explored.
