Asteroid impact in 2032: NASA and ESA give the all-clear

The asteroid 2024 YR4 has given astronomers a week full of ups and downs. In the middle of last week, they had calculated a probability of 3.1 percent that the 40 to 90 meter large rock could hit the Earth on December 22, 2032. That doesn't sound like much. But since asteroids have been regularly monitored, there has never been such a high risk for an object of this size.

But since then, what some experts had predicted has happened: new observations of the asteroid have caused the probability of an impact to plummet. In its latest update on Monday, the European Space Agency (ESA) put the risk at just 0.002 percent, while NASA puts it at 0.004 percent . In both cases, the risk of an impact is therefore negligible.

As a result, 2024 YR4 also slipped down the so-called Turin scale . Astronomers use this scale from 0 (no risk) to 10 (certain collision with global consequences) to assess the danger posed by near-Earth asteroids. For a short time, 2024 YR4 reached level 3, which requires increased attention from astronomers. 2024 YR4 is now back at level 0 and is therefore in the green zone.

How is such an up and down possible in just a few days? In order to estimate the risk of a future impact, astronomers need to know the asteroid's previous trajectory. The further back this trajectory can be traced, the more accurately it can be calculated at what distance it will fly past the Earth on December 22, 2032.

In mid-February, the observation conditions were not particularly favorable. The bright full moon had prevented observations of the faint object. This changed with the waning moon. For a few days now, there have been new observations of the asteroid that have allowed astronomers to refine their calculations.

These calculations are repeated daily. What has remained the same is that the asteroid will fly past the Earth on December 22, 2032 at a distance of less than 300,000 kilometers. This means it will be closer to the Earth than the moon, which orbits the Earth at a distance of 384,000 kilometers. What has changed in the last few days is the range of these calculations. Thanks to the new observations, this has been reduced so much that a collision with the Earth is now almost impossible.

What cannot yet be completely ruled out is a collision between the asteroid and the moon. But according to NASA, this risk is also less than one percent.

Although the danger posed by 2024 YR4 has diminished, astronomers will continue to keep an eye on the asteroid in the coming weeks. There is unlikely to be another opportunity to practice monitoring a potentially dangerous asteroid on a specific object any time soon.

The window for further observations is closing soon. The asteroid will still be able to be tracked with ground-based telescopes until April. After that, it will be too far away from Earth. The last telescope to see it will probably be the James Webb Space Telescope. The aim is to use it between March and May to find out how big 2024 YR4 really is. So far, there are only rough estimates of its diameter.

After that, we will have to wait until 2028. Only then will the asteroid fly past the Earth again and be clearly visible. We can now look forward to this flyby with relative peace of mind. As things currently stand, there is no need to take defensive measures.