In a nutshell: A recent study has revealed that Venus, Earth’s closest planetary neighbor, may harbor a largely undetected population of asteroids capable of crossing Earth’s path over thousands of years. While these space rocks pose no immediate danger, their elusive orbits and proximity to our planet have prompted astronomers to reconsider how we monitor near-Earth objects.
Co-orbital asteroids – space rocks that travel alongside planets without fully orbiting them – are notoriously difficult to track. Venus currently hosts 20 known co-orbitals, including “Trojan” asteroids and the peculiar quasi-moon Zoozve. These objects, each exceeding 460 feet in diameter, could devastate urban areas if they collided with Earth. Simulations suggest their orbits, which are shaped by gravitational interactions with Venus and other planets, might eventually redirect them toward our planet.
“None of the current co-orbital objects will impact Earth soon,” Valerio Carruba, an astronomer at São Paulo State University and lead author of the study, told Live Science.
His team’s research, published on the preprint server arXiv and awaiting peer review, modeled the behavior of cloned hypothetical asteroids with less elongated orbits over a 36,000-year period. The results indicated that some could eventually enter collision courses with Earth, though the likelihood remains uncertain.
Most known Venusian co-orbitals have highly eccentric paths, making them easier to spot during brief observational windows. However, Carruba’s team suggests that many more may exist with lower orbital eccentricities, hidden from view by the Sun’s glare. These stealthy objects could evade detection until they approach Earth, as demonstrated by a recent false alarm involving an asteroid initially thought to have a 2.3 percent chance of striking Earth in 2032, before revised calculations ruled it out.
The study highlights the chaotic nature of these asteroids’ orbits, with Lyapunov times – the period after which their paths become unpredictable – averaging just 150 years. This inherent instability complicates long-term risk assessments, necessitating the use of statistical models rather than single-orbit analyses.
Efforts to spot these threats are set to advance with the Vera C. Rubin Observatory in Chile, which will begin scanning the skies in late 2025. Its wide-field telescope may identify faint asteroids during their fleeting windows of visibility. Yet Carruba argues that Earth-based tools alone may not be enough. “Only a dedicated observational campaign from a space-based mission near Venus could map all the still ‘invisible’ asteroids,” the researchers wrote.
Proposed missions to Venus’ orbital vicinity, such as telescopes positioned at gravitational balance points, could offer clearer views. Meanwhile, Carruba remains cautiously optimistic: “I believe we should not underestimate their potential danger, but I would not lose sleep over this issue. Soon, our understanding of this population will improve.”
Two decades after NASA was tasked with tracking 90 percent of near-Earth asteroids, the discovery of Venus’ co-orbitals underscores the need to expand current search parameters. While existing surveys mainly target objects within 1.3 astronomical units of Earth, Carruba’s research reveals critical gaps in monitoring asteroids tied to other planets.
