A new study published in Astronomy & Astrophysics has revealed a hidden danger lurking close to our solar neighborhood — asteroids that orbit the Sun alongside Venus but remain nearly invisible to telescopes on Earth. These elusive space rocks, known as Venus co-orbital asteroids, could one day shift their paths and threaten our planet, researchers warn.
According to scientists, these asteroids don’t actually orbit Venus itself. Instead, they travel around the Sun in sync with Venus, following it or leading it in looping, unstable orbits. Their positioning, however, makes them extremely difficult to detect. Because they orbit closer to the Sun than Earth does, the glare from sunlight drowns out their reflected light, hiding them from even the most powerful telescopes.
So far, astronomers have only confirmed about 20 known Venus co-orbital asteroids, but experts believe that hundreds more could be out there, completely unseen. Some of these could be hundreds of meters across, large enough to cause catastrophic damage if one were to ever collide with Earth.
“If one of these asteroids hit our planet, it could create a crater several kilometers wide and release energy comparable to hundreds of nuclear bombs,” researchers noted.
—
Why They’re So Hard to Find
Detecting asteroids usually relies on spotting their faint reflection of sunlight. But because these Venus co-orbitals stay close to the Sun’s glare from Earth’s point of view, they’re hidden in daylight. Even advanced observatories like NASA’s NEOWISE or ground-based surveys struggle to pick them up unless they briefly move into darker parts of the sky.
The upcoming Vera Rubin Observatory in Chile, which will soon begin its full-sky survey using the world’s largest digital camera, might help identify some of these hidden bodies. However, even Rubin’s massive 3.2-gigapixel telescope can only detect them during specific times of the year when the geometry between Earth, Venus, and the asteroids lines up just right.
“Most of the time, these asteroids are literally lost in sunlight,” said lead researcher Dr. Valerio Carruba. “It’s like trying to spot a firefly next to a searchlight.”
—
A Shifting Danger
What makes these asteroids particularly worrying isn’t just that they’re invisible — it’s that their orbits are unstable. The study found that their paths slowly evolve over thousands of years due to gravitational interactions with Venus, Earth, and other planets.
Researchers estimate that these orbits can change significantly every 12,000 years, but scientists can only accurately predict their movement for about the next 150 years. After that, the uncertainty becomes too large to know exactly where they’ll go.
That means a currently harmless Venus co-orbital asteroid could, over millennia, shift into an orbit that crosses Earth’s path, turning it into a potential impact threat.
“Even though these objects seem stable now, they can become dangerous in the distant future,” Dr. Carruba explained. “It’s a slow but unpredictable process.”
—
What the Simulations Revealed
To better understand the risks, researchers ran computer simulations tracking how these asteroids move under the influence of planetary gravity. They discovered that some follow complex, looping paths that temporarily lock them into resonance with Venus, while others wander between the orbits of Mercury, Venus, and Earth.
These dynamic behaviors mean they can occasionally cross into Earth’s orbital region, especially when gravitational nudges destabilize them. The simulations also suggested that some of these hidden asteroids could already be on the move toward more Earth-crossing trajectories, but because they’re so hard to detect, scientists wouldn’t notice until it’s too late.
—
Preparing for the Unseen
Astronomers are now calling for dedicated space-based observatories that can look toward the Sun — something ground telescopes can’t do safely. Missions like NASA’s upcoming Near-Earth Object Surveyor (NEO Surveyor), launching later this decade, could provide crucial visibility by operating from space, away from Earth’s atmosphere and sunlight interference.
Finding these asteroids is critical not only for planetary defense but also for understanding how such co-orbital systems evolve. Venus’s gravitational influence may play a larger role than previously thought in shaping asteroid movements across the inner solar system.
“Every new discovery helps us fill in the missing pieces of our solar system’s puzzle,” said Dr. Carruba. “But we’re also learning that there are still many threats hiding in plain sight — and we need to find them before they find us.”
Source:
Carruba, V., et al. “The invisible threat—Assessing the collisional hazard posed by undiscovered Venus co-orbital asteroids.” Astronomy & Astrophysics 699 (2025): A86.