An international team of astronomers led by Valerio Carruba from São Paulo State University in Brazil has discovered a previously unknown group of asteroids sharing Venus’s orbit. These so-called co-orbital asteroids of Venus move in synchrony with the planet around the Sun, making them virtually invisible to Earth-based telescopes. The study, published on the preprint server arXiv and accepted for publication in Astronomy and Astrophysics, suggests that there may be far more of these objects than previously believed.

“It's like discovering a continent you didn't know existed,” said Carruba.

What Are Co-orbital Asteroids of Venus?

Co-orbital asteroids are a rare class of celestial objects that travel along orbits synchronized with a planet—in this case, Venus, the second planet from the Sun. So far, only about 20 of these Venusian co-orbitals have been identified, but researchers believe there could be hundreds. These bodies remain gravitationally linked to Venus, either trailing, leading, or orbiting near it, often in what are called Lagrange points—regions where the gravitational pull of Venus and the Sun create stable zones.

Due to their proximity to the Sun in the sky, most of these asteroids are extremely difficult to detect from Earth. Only one is known to follow a nearly circular orbit, while the rest have elongated trajectories that occasionally bring them near Earth.

Why Are They So Hard to Detect?

Several factors make observing these asteroids challenging:

  • Proximity to the Sun: They appear near the Sun’s glare, making their faint light hard to distinguish with ground-based telescopes.
  • Fast movement: Their high orbital speed makes them appear blurred or streaked in long-exposure images.
  • Small size: With diameters typically ranging from 300 to 400 meters, they are dim and difficult to spot.

Carruba suggests that observational bias skews current statistics—we only detect those that temporarily come close to Earth. There are likely hundreds more, he said, we just can’t see them from Earth.

Simulations and Findings

To investigate further, Carruba’s team conducted computer simulations modeling the orbits of hundreds of hypothetical co-orbital asteroids around Venus. The projections, spanning 36,000 years, indicated that many of these bodies could remain gravitationally bound to Venus’s orbit for an average of 12,000 years. However, their paths are chaotic: even minor changes can redirect them onto different trajectories, some of which bring them closer to Earth.

In a separate study published in Icarus, researchers analyzed the orbits of 20 known Venus co-orbitals. Three of them—measuring 300–400 meters across—may pass within 74,800 kilometers of Earth’s orbit in a few thousand years. Though that’s farther than the Moon (which orbits at about 384,400 km), it’s still considered close in cosmic terms.

“The likelihood of one colliding with Earth any time soon is extremely low,” noted astronomer Scott Sheppard of the Carnegie Institution, who was not involved in the study.

Why Study These Asteroids?

Understanding Venus’s co-orbital asteroids is scientifically valuable for several reasons:

  • Mapping near-Earth space: These findings help refine models of near-Earth objects and assess collision risks.
  • Solar system evolution: These asteroids could be remnants of the early solar system, offering clues about how the inner planets formed.
  • Orbital dynamics: Their chaotic behavior makes them useful case studies for studying gravitational interactions between planets and small bodies.

How to Find Hidden Asteroids?

Traditional telescopes struggle to see near-Sun objects, but emerging technologies and missions may change that:

  • Vera C. Rubin Observatory: Operational since 2025, it has already identified 2,104 new asteroids. Special twilight survey campaigns could help spot Venus co-orbitals.
  • CROWN Mission: A proposed mission involving a fleet of small spacecraft orbiting Venus to hunt for co-orbital asteroids. Proximity would improve detection of fast-moving objects.
  • Space telescopes: Future orbiting observatories like the Nancy Grace Roman Space Telescope may provide better visibility of objects near the Sun.

If these asteroids are out there, such missions will help us find them, said Carruba.

Context Within the Solar System

Venus is not unique in having co-orbital companions. Jupiter has thousands of Trojan asteroids, while Earth has one confirmed co-orbital asteroid: 2010 TK7. However, Venus’s co-orbitals are particularly intriguing because they may be remnants of the primordial material that formed the terrestrial planets. Their composition might reflect the same ingredients that formed both Venus and Earth—including volatile elements like water.

Conclusion

The discovery of a hidden family of asteroids on Venus’s orbit is a leap forward in understanding the “invisible” part of our solar system. Though difficult to observe, these objects may hold key insights into planetary formation and orbital dynamics. With advanced observatories like the Vera Rubin and future missions like CROWN, astronomers are poised to uncover more of these elusive space rocks. As Carruba put it, “they’re dynamically fascinating”—and studying them could unlock new knowledge about our cosmic neighborhood.