A hidden swarm of asteroids orbiting with Venus may be silently drifting toward Earth—and we might not see them coming until it's too late.
A new study titled The Invisible Threat: Assessing the Collisional Hazard Posed by the Undiscovered Venus Co-Orbital Asteroids raises alarms about a poorly understood population of Venus co-orbital asteroids that could pose a serious risk to Earth. Authored by Valerio Carruba and colleagues at São Paulo University , the research highlights the dangers of these elusive bodies—some of which may be nearly impossible to detect from Earth-based observatories. Unlike most near-Earth asteroids (NEAs) that have been the focus of NASA's tracking initiatives for decades, these particular space rocks share their orbit with Venus , making them harder to locate and potentially more unpredictable.
Hidden in Plain Sight: The Orbital Camouflage of Venusian Co-Orbitals
Although Jupiter's Trojan asteroids are well-documented, Venus's co-orbital population is only beginning to be understood. The researchers reveal that “twenty co-orbital asteroids of Venus are currently known,” noting a key vulnerability: “co-orbital status protects these asteroids from close approaches to Venus, but it does not protect them from encountering Earth.” These asteroids are classified as potentially hazardous asteroids (PHAs) if they have “a minimum diameter of about 140 meters and come within 0.05 astronomical units (au) of Earth's orbit,” they explain. Such dimensions are more than sufficient to unleash catastrophic destruction if one were to impact Earth. The dual orbit-sharing and near-Earth intersecting characteristics make these asteroids doubly dangerous and hard to predict, unlike more conventional NEAs which follow clearer and better-studied paths through the inner solar system.
The Chaos of Orbital Evolution and the Limits of Prediction
The key concern with these Venusian co-orbitals lies in their highly chaotic trajectories, which the study quantifies using Lyapunov times —a metric that indicates how quickly an object's orbit becomes unpredictable. The simulations conducted by Carruba's team show that even a slight difference in orbital parameters can lead to vastly different long-term paths. “We aim to assess the possible threat that the yet undetected population of Venus co-orbiters may pose to Earth, and to investigate their detectability from Earth and space observatories,” the authors write. Their research used clone asteroids to simulate a range of possible futures over 36,000 years. These simulations confirm that even co-orbitals with low eccentricities—those previously thought less dangerous—could eventually cross Earth's path, especially if disturbed by gravitational interactions or solar radiation forces. As their orbits evolve over time, they drift into Earth's neighborhood, posing impact risks that current monitoring systems may miss entirely.
Observability Bias and the Limits of Ground-Based Detection
Most Venusian co-orbitals are nearly invisible from Earth because they often remain in the Sun's glare. This observational constraint introduces a dangerous blind spot. As the authors note, “there is a range of orbits with eccentricity < 0.38, larger at lower inclinations, for which Venus' co-orbitals can pose a collisional hazard to Earth.” These low-eccentricity asteroids are particularly worrisome because they are harder to spot and predict. The upcoming Vera Rubin Observatory , expected to begin full operations in July 2025, could potentially detect some of these objects during specific observational windows—times when the Sun's position allows for a brief glimpse of otherwise hidden threats. Yet these windows are fleeting and narrow, raising concerns that even advanced Earth-based telescopes might not suffice. Without continuous and dedicated surveillance from a more advantageous location, a significant portion of the PHA population could remain completely undetected.
The Case for a Dedicated Space-Based Observatory Near Venus
Recognizing the limits of Earth-based detection, Carruba and his team advocate for more space-based surveillance initiatives. A mission placed in Venus's orbit , particularly one positioned to look away from the Sun, could vastly improve our ability to detect and monitor these elusive PHAs. “Among these, low-e Venus co-orbitals pose a unique challenge, because of the difficulties in detecting and following these objects from Earth,” the authors write in their conclusion. They emphasize the potential of placing observatories in Lagrange Points such as Sun–Earth or Sun–Venus L1/L2 to maximize coverage of the region. “While surveys like those from the Rubin Observatory may be able to detect some of these asteroids in the near future, we believe that only a dedicated observational campaign from a space-based mission near Venus could potentially map and discover all the still ‘invisible' PHA among Venus' co-orbital asteroids,” the researchers conclude. This level of surveillance would be the only way to address the knowledge gap that currently leaves Earth vulnerable to surprise impacts.