Scientists have identified a hidden population of asteroids that could pose a serious threat to Earth, even though we can’t see them with current telescopes.
These objects, known as Venusian co-orbital asteroids, share their orbit with Venus and remain extremely difficult to detect because of their position in the sky.
A new study led by researchers at São Paulo State University (UNESP) in Brazil warns that some of these asteroids could one day cross Earth’s path and, in rare cases, collide with our planet.
“These objects orbit the sun in the same time as Venus, but they are not part of the asteroid belt between Mars and Jupiter,” explained astronomer Valerio Carruba, lead author of the study published in Astronomy & Astrophysics.
“Because of their position, they remain invisible to our telescopes, even though they may be dangerous in the long term.”
The researchers used advanced computer models and long-term simulations to track how these hidden asteroids might behave.
They found that Venusian co-orbitals are highly unstable, often switching orbital patterns in cycles lasting about 12,000 years.
During these transitions, they can wander close to Earth’s orbit, raising the risk of a potential collision.
So far, astronomers have cataloged only 20 of these objects, nearly all with elongated orbits that make them easier to spot when they move farther from the sun.
But the models suggest there could be many more with near-circular orbits—making them virtually invisible from Earth-based observatories because they stay too close to the sun’s glare.
The danger comes from their size and impact potential. Simulations suggest that some of these asteroids could be 300 meters wide—large enough to create craters several kilometers across and release energy equivalent to hundreds of megatons of TNT. An impact on a populated region would cause catastrophic destruction.
Detecting them is a major challenge.
Even with the new Vera Rubin Observatory in Chile, simulations show that the brightest Venus co-orbitals would only be visible for one or two weeks at a time and then vanish for months or years. That makes it nearly impossible to track them consistently with current ground-based programs.
The researchers argue that space-based observatories focused on areas close to the sun may provide the answer. Missions such as NASA’s upcoming Neo Surveyor and China’s proposed Crown telescope could scan the skies from different vantage points and spot these hidden objects before they pose a danger.
“Planetary defense needs to consider not only what we can see, but also what we cannot yet detect,” Carruba emphasized.
As for their origin, scientists believe Venus’s co-orbitals were once part of the main asteroid belt between Mars and Jupiter.
Gravitational interactions with Jupiter and Saturn gradually nudged them into inner orbits, where some were temporarily captured by Venus’s gravitational influence.
These captures don’t last forever: eventually, the asteroids either escape the orbit, cross Earth’s path, or are ejected from the solar system entirely.
For now, the threat is not immediate, but the study highlights an important gap in our defenses.
While many near-Earth asteroids have already been mapped, invisible populations like Venus’s co-orbitals remind us that there are still blind spots in our cosmic neighborhood.
Source: KSR.
