The Venus Trap: Undiscovered Asteroids That Could Devastate Earth By David Freeman - May 26, 2025
A growing concern is quietly orbiting just out of sight. While much attention has been placed on near-Earth asteroids crossing our planet’s path, a far less visible threat may be approaching from an unexpected direction: the orbit of Venus. A new study has sounded the alarm on a little-known class of asteroids, Venus co-orbitals, that may be far more dangerous than previously realised. The problem is not just their speed or trajectory. It is that most of them have not even been detected.
Despite decades of telescopic sky surveys, only twenty asteroids have ever been identified in a 1:1 orbital resonance with Venus. That means they travel around the Sun at the same average distance as Venus, occasionally looping ahead or behind the planet in strange gravitational paths. These include tadpole-shaped patterns near the Lagrangian points, horseshoe-like arcs, and retrograde satellite orbits. Yet nearly all known examples share a troubling pattern. They have high orbital eccentricities, meaning their paths are stretched and allow them to swing dangerously close to Earth.
At least six of these co-orbitals are already classified as potentially hazardous asteroids, based on how close they can pass to Earth. Three of them are particularly alarming. Asteroids 2020 SB, 524522, and 2020 CL1 have minimum orbital intersection distances with Earth of less than 0.0005 astronomical units, which is less than one-fifth the distance to the Moon. Their estimated sizes range between 300 and 390 metres, large enough to obliterate a city. If any of them were to strike Earth, the resulting explosion would release energy equivalent to between 1.5 and 4.1 × 10² megatons of TNT, forming craters more than three kilometres wide. These impacts would fall into category 8 on the Torino scale, indicating regional devastation from land strikes or tsunami-generating coastal impacts.
But those are only the ones we know about. The more urgent problem is what remains hidden in the dark.
The reason we have detected so few Venus co-orbital asteroids is not because they are rare. It is because the majority of them are likely invisible to our current sky surveys. The real danger may lie in what has not yet been seen.
Ground-based observatories rely heavily on night-time visibility and favourable angles relative to the Sun. Objects near Venus’ orbit are notoriously hard to observe from Earth because they spend most of their time in the daytime sky or too close to the Sun’s glare to be spotted. Those with low eccentricity orbits, which do not swing far away from the orbit of Venus, never come close enough to Earth to appear bright in our skies. They remain locked in the inner solar system, hidden in the twilight zones just beyond the reach of our telescopes.
The study by Carruba and colleagues confirms that this is not due to a lack of such asteroids in nature. Using one of the most advanced near-Earth object population models to date, known as NEOMOD3, the team simulated thousands of asteroid trajectories within the orbital zone around Venus. Their results show a wide and evenly distributed population of objects with all levels of eccentricity, including many with low values below 0.38. Yet nearly all currently known Venus co-orbitals are above this eccentricity threshold. This indicates a major observational bias. Our instruments are more likely to spot those with stretched orbits that wander into Earth’s neighbourhood, leaving the stable, circular ones near Venus essentially undetected.
This is a critical point. Low-eccentricity co-orbitals of Venus may be the silent majority. They orbit harmlessly for thousands of years, trapped in gravitational resonance, until they shift orbit enough to escape this locked configuration. Once they do, they can become dangerous. The transition from a Venus Trojan to a wandering Earth-crossing asteroid is a chaotic one. These objects do not remain permanently locked in their orbital paths. Most spend only about 12,000 years in a stable co-orbital state before their motion begins to drift. Over time, they can enter circulation patterns that bring them much closer to Earth.
The researchers simulated many such orbital evolutions, placing hundreds of test particles in potential Venus co-orbital configurations and watching how they behaved over long timescales. They found that even within the most stable, low-eccentricity range, a significant number of these objects could evolve into paths that bring them near Earth. The danger is not immediate, but it accumulates. The longer these bodies go undetected, the greater the chance that one could eventually slip through the cracks.
At least five of the known Venus co-orbitals are already moving along tracks that bring them within 0.0005 astronomical units of Earth’s orbit. These are not hypothetical future threats. They are real asteroids that already exist, large enough to destroy cities, and difficult to observe except under the best conditions. If even a fraction of the unseen population behaves similarly, the number of near-Earth threats could be much higher than current estimates suggest.
understand how serious this invisible threat could be, the team conducted long-range numerical simulations of possible impact scenarios. These were not simple projections. The analysis covered 36,000 years of orbital evolution, enough to observe multiple complete transitions in and out of Venus’ co-orbital zone. This timeframe spans three full co-orbital cycles, which is the average lifespan for an asteroid locked in 1:1 resonance with Venus.
Each simulation started with test particles placed into orbits consistent with known gravitational dynamics, then followed them through space as they interacted with the gravity of all eight planets. What emerged was a disturbing pattern. Even objects that started off in stable, low-eccentricity orbits—previously thought to pose minimal danger—were found to drift into paths that brought them increasingly close to Earth.
The danger zone was clearly defined. Asteroids with an eccentricity near 0.38, the threshold where a Venus co-orbital’s orbit just touches Earth’s, were by far the most likely to have close encounters. But it was not limited to that narrow range. Several configurations at even lower eccentricities and low inclinations—meaning objects that stay close to the plane of Venus’ orbit—showed consistent potential for eventual intersection with Earth’s path.
This is not just theoretical. Real data from known asteroids shows that some of them already cross into this critical range. Based on their size, composition, and approach distance, if any of them were to impact Earth, the consequences would be catastrophic. A strike from one of the 300 to 400 metre-wide candidates would exceed the energy of most nuclear arsenals on the planet. These are not extinction-level objects like the one that ended the dinosaurs. But they are more than capable of wiping out a major metropolitan area, triggering regional climate disruptions, and producing tsunamis along coastlines.
The most dangerous orbits were found among low-eccentricity objects with low inclinations. These are the ones that surveys are least likely to detect, due to their limited brightness and the fact that they remain hidden in the glare of the inner solar system. Yet simulations showed that several of these hypothetical asteroids made repeated close approaches to Earth over the 36,000-year test period. Some passed well within the Moon’s distance. A few dipped inside the orbital distance of Earth itself.
In most cases, the trajectories were chaotic. That means they were sensitive to small gravitational nudges from nearby planets, causing their paths to change rapidly over time. This chaotic behaviour makes it almost impossible to predict individual impacts far in advance. What it does allow, however, is a statistical projection of threat. The more of these objects that exist—and the simulations suggest there are many—the greater the chance that one will eventually collide with Earth.
One simulation tracked five specific test objects, all with eccentricities below 0.38. These were selected because they experienced either the highest number of close Earth encounters or passed within the closest distances during the study period. Every one of them showed multiple flybys that would qualify as hazardous under international asteroid risk guidelines. These orbits were not extreme outliers. They were within the expected range for Venus co-orbitals, suggesting that similar bodies may be present right now, still undetected.
Despite their potential danger, these asteroids are nearly invisible to even the best observatories on Earth. The problem is geometry. Venus co-orbitals remain close to the Sun in the sky from our point of view. That limits when and how they can be seen. They are only visible during narrow windows just before sunrise or after sunset, when the sky is not yet fully bright and the object happens to be far enough from the Sun’s glare to be picked up by telescopes.
Surveys like the one being prepared by the Vera C. Rubin Observatory in Chile will help, but even that will only catch a fraction of them. The team ran observability simulations using Rubin’s projected capabilities, testing both known co-orbitals like 2020 CL1 and a set of synthetic test objects based on the dangerous orbits found in simulations. They found that these asteroids do become visible from Earth at certain times, but the opportunities are short and infrequent. Most remain above the necessary minimum elevation of 20 degrees for just a few weeks at a time, once every few years.
Brightness is another problem. The test objects are assumed to have absolute magnitudes of 22, which is dim but within the detection range of Rubin’s 23.5 single-visit threshold. Still, even when technically visible, these objects are often too close to the Sun to be targeted consistently. Objects with higher eccentricities, which travel farther from the Sun and get closer to Earth, are easier to detect. This naturally biases our surveys in favour of the ones that have already become dangerous, and against those that are still quietly orbiting in the Venus zone.
The observatory data showed a clear trend. Higher eccentricity meant more frequent and longer detection windows. Lower eccentricity meant shorter, rarer opportunities. Inclination had less effect. Whether the orbit was tilted or not, detectability remained about the same. What mattered most was how close the object could get to Earth. If it stayed close to Venus, the chances of it ever being seen dropped significantly.
This helps explain why nearly all currently known Venus co-orbitals have eccentricities above 0.38. It is not that lower-eccentricity versions do not exist. The simulations show they should be common. But their orbits keep them hidden in the glare, just out of reach.
The study also explored what could be done to improve detection. The answer lies in space, and more specifically, near Venus.
Observing from Earth has fundamental limits. There is no way around the fact that the Sun blocks large sections of the sky. Telescopes placed in space, especially near Venus, would be in a much better position. A telescope in orbit around Venus or near one of its Lagrangian points could scan the inner solar system continuously, without the solar interference that affects ground-based instruments.
Several mission concepts have already been proposed to do just that. One idea involves placing a space telescope in a halo orbit around the Sun-Venus L2 point, facing outward from the Sun. Another calls for a constellation of small satellites placed in Venus-like orbits, each with a telescope looking back toward the Earth’s orbital path. These would offer overlapping coverage, reduce observational gaps, and allow for more precise tracking of any objects detected.
One such proposal, called CROWN, envisions a seven-part system with one mothership and six deployable telescopes. The team behind it claims this setup could provide 100-day continuous observation arcs for over 94 percent of simulated targets. That level of coverage would revolutionise asteroid tracking in the inner solar system and finally bring Venus co-orbitals out of hiding.
Space-based infrared observatories like NEO Surveyor, scheduled for launch after 2027, will also help. While it will operate from a halo orbit near Earth rather than Venus, it is designed to detect the thermal signatures of dark, hard-to-see objects that reflect little visible light. Its sensors can detect objects at solar elongations as low as 45 degrees, potentially capturing some of the currently invisible low-eccentricity co-orbitals.
In December 2024, a newly discovered asteroid named 2024 YR4 was briefly listed as the highest-impact-probability object ever recorded above 20 metres in size. It came from the same general region as many Venus co-orbitals. For several days, the probability of impact was among the highest ever calculated. It has since been ruled out, but the event highlights the problem. There are still objects in the inner solar system large enough to cause severe damage that we have never seen before.
The discovery of just one such object should be a wake-up call. The simulations suggest that dozens, possibly hundreds more are waiting to be found, locked in the orbit of Venus, passing invisibly in and out of co-orbital configurations. Most of them are small enough to go unnoticed but large enough to cause devastation if they strike.
The paper concludes that only a dedicated campaign of space-based observation, especially from orbits near Venus, can map the true scale of this invisible population. Until then, Earth remains exposed to a class of potential impactors that almost no one is watching.
Source:
arruba, V., Sfair, R., Araujo, R. A. N., Winter, O. C., Mourão, D. C., Di Ruzza, S., Aljbaae, S., Caritá, G., Domingos, R. C., & Alves, A. A. (2025). The invisible threat: Assessing the collisional hazard posed by the undiscovered Venus co-orbital asteroids. arXiv preprint arXiv:2505.15968v1.
ChristopherBlackwell
This is all based on simulations and possible existence, not actual knowledge
I think it's a great idea to send up those satellites to be able to better SEE if any of the presumed additional Venus linked asteroids exist. However, I'm not going to worry too much about simulated assumptions for now.
on May 26, 2025, 4:48 pm
