Will an asteroid really hit Earth in 2032? Why we shouldn't worry (yet)

The blue planet threatened by an asteroid in the coming years? According to NASA, the asteroid YR4 , discovered in December 2024, could hit Earth in less than a decade. According to the latest observations by the American space agency , carried out with a powerful telescope located in Chile, YR4 presents a 2.3% risk of hitting our planet in 2032. The first calculations suggested a risk of 1.2%, but it has since been raised.

This threshold is considered both "low" and "sufficiently relevant" for the asteroid to be closely monitored, Patrick Michel, doctor of astrophysics and research director at the National Center for Scientific Research (CNRS) at the Côte d'Azur Observatory, explained to BFMTV.com.

The upward revision of this risk is based on new observations, according to the scientist. "It has increased a little, but there is no reason to be alarmed," assures the author of À la rencontre des asteroïdes (Odile Jacob editions), specifying that this reassessment is normal. "All over the world, we are tracking this object, we are following its trajectory," which inevitably leads, according to him, to changes in the probabilities of collision.

"The risk exists, but we should not worry," astrophysicist Éric Lagadec told BFMTV.com. "The more we observe the asteroid, the more we will know its trajectory," he emphasizes.

Since 2017, astronomers in the UN's International Asteroid Alert Network have established an alert threshold whenever a celestial object of at least 10 metres in size with at least a 1% probability of hitting the Earth is identified.

With the asteroid YR4, "this is the first time that an object meets the established criteria", a sign of the importance of the discovery, notes Patrick Michel. For him, however, it is far from being a source of concern.

"Immediately, when the criteria were exceeded, we met by videoconference to be transparent and not to panic people," explains the scientist, a member of the international asteroid warning committee at the UN. For him, the threshold set is deliberately low, as a precaution.

"The 1% risk threshold gives us time to react," assures the researcher.

Although the probability of impact has increased in recent weeks, experts point out that the asteroid still has a nearly 98% chance of not hitting our planet.

"The increase in probability is not necessarily a sign that a collision is increasingly certain," says Patrick Michel, as the probability threshold could easily reverse in the coming weeks and fall back to zero.

The researcher notes that the trajectory of the asteroid remains so uncertain at present that its possible impact zone is as wide as "several times the Earth-Moon trajectory". Enough to still leave a great deal of uncertainty over the possibility of a terrestrial impact.

For now, the diameter of the asteroid YR4 is estimated at between 40 and 90 meters. If it reaches the size established in the lower range, it could destroy "a large city", according to Patrick Michel, and in the higher range "a large region". We are still a long way, despite everything, from the dimensions of the 10 kilometer diameter meteorite that precipitated the extinction of the dinosaurs more than 60 million years ago.

But don't panic. Even in the event of a collision, the Earth remains mostly covered in water and desert, making it very unlikely that a city would be wiped off the map.

Knowing the dimensions of the asteroid more precisely seems essential, as does identifying the materials it is composed of, in order to assess the risks. "The possible damage depends on its density. However, we don't know what it is made of, but we are working on it," assures Patrick Michel.

"We don't yet know the risks, it will become more precise with new observations," summarizes Éric Lagadec.

According to scientists' calculations, the asteroid will continue to be visible until next April, then disappear from our field of vision until 2028. "By then, the probability of collision will either decrease or increase, potentially up to 20%," estimates Patrick Michel.

It will only be then, in 2028, that the space agencies committee will eventually decide whether to put a plan in place to anticipate a possible collision between the asteroid and Earth.

"For the moment, there is no reason to act," assures Patrick Michel.

In the event that intervention becomes necessary, several options are on the table. If predictions indicate that the asteroid will fall into an ocean, scientists could simply let the object go to the end of its trajectory.

"If as a last resort, we can try to deflect it by pushing it" with a vessel as was successfully done with the DART probe in 2022, but "with the risk of breaking it into several pieces and creating more impacts," says Éric Lagadec. "Otherwise, (as) its trajectory is influenced by the interaction with sunlight, paint it in another color could change its trajectory," he adds. To do this, it would be necessary to send a spacecraft into orbit. However, the technique remains very uncertain at present.

Finally, blowing up the asteroid when we don't know what it is made of seems risky, especially since it would also create different pieces that would fall onto the surface of the Earth.

A new powerful telescope, called the Vera C. Rubin, is to be installed in Chile this year, which should allow even more precise observation of the asteroids threatening the blue planet. "It's going to cause an explosion of discoveries," warns Patrick Michel.