Venus's hidden asteroids could be Earth's next major impact risk

Yahoo

29-05-2025

It may look like Earth's twin, but Venus is keeping secrets.
New research suggests that dozens—possibly hundreds—of asteroids are quietly orbiting the Sun in sync with Venus. Known as Venus co-orbitals, these stealthy rocks follow a similar path around the Sun, making them difficult to spot from Earth.
For a long time, experts have only known about 20 of them, and most have been easier to spot. However, new research suggests a significant yet undetected population of these asteroids.
"Twenty co-orbital asteroids of Venus are currently known. Co-orbital status protects these asteroids from close approaches to Venus, but it does not protect them from encountering Earth," a team led by Valerio Carruba, an assistant professor at São Paolo University in Brazil, wrote in the study paper.
Venusian co-orbital asteroids are classified as Potentially Hazardous Asteroids (PHAs) if they are at least 140 meters (460 feet) in diameter. In terms of distance, these asteroids are calculated to approach Earth's orbit within 0.05 astronomical units (4.6 million miles).
An important question researchers are investigating is whether these objects pose a genuine collision threat to Earth or not.
'We aim to assess the possible threat that the yet undetected population of Venus co-orbitals may pose to Earth and investigate their detectability from Earth and space observatories,' the study noted.
The team suspects the known 20 Venus co-orbitals are just the tip of the iceberg. It could be even more challenging to spot Venus's hidden co-orbital asteroids.
Current ground-based telescopes face limitations in detecting Venus co-orbital asteroids due to fleeting observation windows and the Sun's bright glare.
A particularly unsettling aspect is that these asteroids have a "Lyapunov time" of roughly 150 years.
Universe Today explained that the Lyapunov time measures the point at which an object's orbit enters a chaotic, unpredictable state.
In a nutshell, experts might be able to monitor the path of asteroids for a while, but the future orbital behavior will remain unpredictable.
This makes it challenging to assess whether they will have a close encounter with Earth or even a collision.
Researchers digitally replicated these hidden asteroids and conducted 36,000-year orbital simulations to understand the potential threat.
The findings are alarming: "There is a sizable population of potential co-orbitals at lower eccentricity capable of numerous close encounters—and perhaps collisions—with Earth."
"There is a range of orbits with e < 0.38, larger at lower inclinations, for which Venus' co-orbitals can pose a collisional hazard to Earth," the study added.
The results indicate that the asteroids with eccentricities below 0.38 could strike Earth.
Eccentricity measures how stretched out an orbit is. An eccentricity of 0 means a perfectly circular path, while larger numbers indicate a more elongated ellipse.
In terms of studying the hidden asteroids, the upcoming Vera Rubin Observatory offers hope. Its incredibly powerful camera may help us catch some elusive objects under favorable conditions.
But even Rubin's capabilities might not be enough to find the entire population. The researchers suggest that a space-based observatory, perhaps a constellation of spacecraft near Venus, could be our best bet.
NASA has already taken a step towards planetary defense by successfully executing the DART asteroid mission. In the worst-case scenario, it could prevent a catastrophe similar to the one that led to the extinction of the dinosaurs.
However, accurately predicting the precise path of these Venus co-orbitals is critical for any successful deflection effort.
The study is posted on the pre-print server arXiv.org; it has also been submitted for publication in Astronomy and Astrophysics.