According to the cneos calculations (Center for Near Earth Object Studies) from the Nasathe chances that theAsteroid 2024 YR4 – just discovered fifty days ago and the size of 40-90 meters – hit the earth the 22 December 2032 they are practically halved in the night between 19 and 20 February, passing from 3.1% to a more modest 1.5% After 376 observations of the motion of the celestial body. To be clear, 3.1% is the probability of impact never recorded for an asteroid, beating the 2.7% record set in 2004 by the Asteroid Apophis (whose possible impact with our planet was excluded with further observations).
These continuous probability oscillations they don’t have to worry about. What is happening is exactly what was expected. As we have already had the opportunity to explain, in fact, when an asteroid Near-Earth It is discovered in the sun system, the chances of impact they tend to grow over time and then decrease Up to practically zero.
We can explain it so. Suppose that at the moment of maximum approach between the Earth and 2024 YR4, scheduled for December 22, 2032, the most likely distance will be 100,000 km. And we also suppose that currently ours uncertainty On this distance of 200,000 km (they are random numbers, just to give an example). At the moment of maximum approach, therefore, the asteroid could be at any point inside a sphere of radius 200,000 km around the real point in which it will be located. And this sphere certainly contains the earth, therefore the possibility of an impact it cannot be excluded. As long as the uncertainty about the distance of maximum approach is greater than the distance itself, there will be a probability of impact with the earth.
As new observations are collected on the asteroid motion, the uncertainty about the distance of maximum approach gradually decreases. In short, the “sphere” becomes smaller and smaller, but the earth always remains inside and for this reason the probability of impact with our planet tends to increase. At a certain point, however, uncertainty becomes smaller than the real distance: Here the sphere of the possible positions of the asteroid at the time of the maximum approach no longer contains the earth and therefore the probability of impact collapses to zero.
In conclusion, have a probability that increases quickly and then decreases it is perfectly normal And it happens with many asteroids Near-Earth recently discovered. In the specific case of 2024 YR4, it is talking about a lot because the chances are high, not so much in absolute terms but in relation to the probability calculated for other asteroids immediately after their discovery.
However, NASA is not the only space agency to calculate the probability of impact with asteroids nEar-Earth. Also the ESA, theEuropean Space Agencyestimates these possibilities even if with different algorithms for the calculation of uncertainties. For this reason, the percentages estimated by ESA can differ from those calculated by NASA. The last update in this sense by the European Space Agency dates back to Tuesday 18 February, with a probability of impact calculated at 2.8% (against 3.1% calculated by NASA). The updated data of the ESA will almost certainly follow the same quick decrease in advance by NASA.
