An asteroid will pass close to Earth on Saturday June 27 without risk of collision. At the very beginning of the afternoon, it will be 2.5 million kilometers from us, the equivalent of more than six times the distance between the Earth and the Moon, and will be observable with small telescopes or large binoculars, said the European Space Agency (ESA). “A close passage of the Earth by an object of this size only occurs every few years,” notes Juan Luis Cano, of the ESA planetary defense office, quoted in a press release.
Spotted in 1997, and named 1997 NC1, it would measure between 750 m and 1.7 km in diameter. Unlike comets, asteroids are inert celestial bodies, composed mainly of rocks, metals and ice. Most of them orbit the Sun, in an area called the “asteroid belt”. Some deviate from it, and their trajectory can then intersect the orbit of other planets. If they are Earth, they are called near-Earth or NEO. When they reach the ground, they are called meteorites.
It is therefore not uncommon for such a celestial object to impact our planet. If most fall to the ground in the form of dust, disintegrated upon entering the atmosphere, “NASA estimates that it “rains” more than 230 meteorites weighing more than 10 g every day on Earth,” specifies the CNRS. Sometimes, however, some can cause impressive collisions, creating gigantic craters.
Variable consequences
Thus, 66 million years ago, an asteroid 12 km in diameter crashed into the blue planet, contributing to the disappearance of the dinosaurs. Much more recently, in 1908, another exploded over Siberia, destroying around 2,000 km2 of forest. Also in Russia, a third, around twenty meters in diameter, exploded in 2013 above Chelyabinsk, injuring more than a thousand people.
The consequences of such an event depend on the size of the asteroid, its speed and the areas affected. According to the ESA, “a near-Earth object of around fifty meters in diameter hits the Earth every 100 to 300 years and an object of one kilometer in diameter every few thousand years”. A study published in 2025 by the American Astronomical Society establishes that the probability of a large asteroid hitting the Earth is higher than that of being struck by lightning – which nevertheless remains infinitesimal.
Beyond 1 km in diameter, the impact could have global consequences, such as the destruction of a country or even a continent. However, as the Earth is more than 70% covered by oceans, the risk of an asteroid falling on an inhabited area is limited. Scientists nevertheless remain on alert. Several defense programs are being carried out at the global level. The United States, Europe and Japan have also created their own organizations dedicated to this discipline.
Thanks to probes and satellites sent into space since the 1990s, as well as increasingly efficient modern telescopes, it has become possible to identify asteroids over 140 m in diameter that evolve in our system. This inventory, in which amateur astronomers also participate, however, remains incomplete: “For the moment, we only know 40% of them,” warns Patrick Michelau, astrophysicist at the CNRS, cited by Figaro Magazine.
In 2029, an exceptional phenomenon
Beyond monitoring these potentially dangerous objects, space agencies are also developing strategies to prevent an impact with Earth by slightly modifying the trajectory of threatening asteroids. Among the techniques studied is kinetic diversion, which involves using the energy of a very high-speed collision to alter their orbit.
In September 2022, NASA’s Dart probe (Double asteroid redirection test) deliberately collided with the Didymos system, located approximately 11 million kilometers from our planet and composed of a main asteroid accompanied by a small satellite. This world first proved conclusive. According to a study published in March 2026, the impact not only modified the satellite trajectory but also influenced the orbit of the main asteroid.
Research efforts continue. In 2029, the European Space Agency (ESA) will launch the Rapid Apophis Mission for Space Safety (Ramses), which will accompany the asteroid Apophis as it passes near Earth. Although this flight presents no danger, it will constitute an exceptional event due to its rarity and proximity. The mission will aim to observe the asteroid in detail as Earth’s gravity modifies its physical characteristics, in order to improve understanding of these objects and strengthen planetary defense capabilities.
