We might be missing a group of asteroids that could threaten Earth. These asteroids are tricky to spot because they orbit near Venus, making them difficult to detect from our perspective.
Since these asteroids lie closer to the Sun than we do, looking for them means peering directly into the sunlight. That makes it hard to see them, as their light is often overwhelmed by the Sun’s glare.
According to astronomer Valerio Carruba from São Paulo State University, “Our study shows that there’s a population of potentially dangerous asteroids that we can’t detect with current telescopes.” These asteroids don’t belong to the asteroid belt between Mars and Jupiter; instead, they orbit the Sun alongside Venus. Unfortunately, they remain hidden, yet could one day pose a real collision risk with Earth.
Currently, astronomers have only identified 20 asteroids co-orbiting with Venus. These asteroids don’t directly orbit Venus but move in a synchronized path around the Sun. Their orbits are complex and can change over time, making them even harder to track. In fact, scientists can predict their paths only for about 150 years into the future.
When one of these asteroids shifts its orbit, it could come near Earth, potentially crossing our path. Carruba warns that behind the 20 known asteroids lies a hidden population, possibly numbering in the hundreds. “Asteroids around 300 meters wide could create craters several kilometers wide,” he notes. An impact from one of these asteroids in a populated area could lead to severe consequences.
Interestingly, many of the known Venus co-orbitals have high eccentricity—meaning their orbits are elongated rather than circular. Earth’s orbit has a low eccentricity of 0.017, making it fairly round. The higher an asteroid’s eccentricity, the more it can travel towards Earth, making it visible at times when the Sun is below the horizon.
Carruba and his team ran simulations to study lower-eccentricity Venus co-orbitals, assessing their potential threat to Earth and how well future observatories can detect them. Their findings suggest there are indeed lower-eccentricity orbits that could be concerning. However, the upcoming Vera Rubin Observatory may only catch these asteroids during specific windows throughout the year.
This gap in knowledge is alarming for planetary defense. It’s tough to guard against a threat you can’t see. One proposed solution is to send an observatory into orbit around Venus. This would help in spotting the asteroids more efficiently. NASA’s NEO Surveyor mission is also aimed at addressing this challenge in the inner Solar System.
Researchers believe that only a dedicated campaign from a space mission close to Venus can truly map and discover the remaining hidden asteroids. Their findings are published in Astronomy & Astrophysics.
This ongoing research highlights the importance of expanding our observational capabilities to better understand asteroids that may pose a threat to our planet, providing a fresh perspective on potential risks from the depths of our own Solar System.
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