by In January 2025 I prepared for my class early morning when I received a message about an asteroid called 2024 YR4. The likelihood that she could hit the earth is unusually high.
Since the defense of the earth before unexpected intruders like asteroids is part of my specialist knowledge, I immediately started to receive questions from my students and colleagues what happened.
When scientists discover an asteroid whose trajectory takes it near the earth, they often monitor it and calculate the likelihood that they collide with our planet. If you receive more observation data, you get a better picture of what could happen.
Having more data points early does not make the predictions of the scientists better. You have to continue to follow the asteroid while moving through the room to better understand his trajectory.
After I thought about the incident a few months later, I wondered if there was a better opportunity for scientists to communicate with the public about the risk. We received precise information, but how the questions I heard did not always show to understand what it actually means.
Numbers change every day
The 2024 YR24-Saleroid has a diameter of 60 meters (approximately 196 feet).
At the time of the announcement in January, the probability of effectiveness of the asteroid was reported over 1%. The probability of effect describes how probably a dangerous asteroid is to hit the earth. For example, if the probability of effect is 1%, it means that it hits the earth in 1 out of 100 cases. Each 100 is rare, but still too close for comfort when talking about the probability of a collision that the earth could destroy.
In the course of time, however, further observations and analyzes showed an almost zero probability that this asteroid collided with the earth.
After the initial announcement in January, the probability of effect on February 18 increased up to 3.1% continuously, but fell to 1.5% on February 19. Then the likelihood of effectiveness increased continuously until it reached 0.004% on February 24th. From June 15, it now has an impact of less than 0.0000081%.
But while the likelihood of hit the earth drops, the likelihood that the asteroid hit the moon increased. On February 24th it rose to 1.7%. From April 2, it will be 3.8%.
If it hits the moon, some outcast materials from this collision could reach the earth. However, these materials would burn away if they enter the thick atmosphere of the earth.
Probability of effectiveness
In order to see if a closer object could hit the earth, researchers find out what a asteroid orbit looks like a technique called astrometry. This technology can determine the orbit of an object just a few kilometers of uncertainty. However, astrometry requires precise observation data for a long time.
Any uncertainty in calculating the orbit of the object leads to variations in the predicted solution. Instead of a precise orbit, the calculation usually gives scientists a cloud of their possible orbits. The ellipse that encloses these places is called Ellipse error.
The probability of effect describes how many orbital predictions make the earth in this ellipse.
Without sufficient observation data, orbital uncertainty is high, so that the ellipse tends to be large. In a large ellipse, there is a higher probability that the ellipse “accidentally” will include the earth – even if the center of the planet is located. Even if an asteroid ultimately does not hit the earth, the mistake of the errors could possibly still contain the planet before scientists collect enough data to narrow down the insecurity.
When the degree of uncertainty drops, the ellipse shrinks. So if the earth is in a small error lips, the probability of impact can be higher than with a large error lips. As soon as the Ellipse error shrinks so high that it no longer contains the earth, the probability of effectiveness drops significantly. That happened at 2024 year 4.
When the ellipse’s error shrinks, the likelihood that the asteroid beats the earth is either below or up when it overlaps with the earth. Toshi Hirabayashi
The probability of effect is a single practical value that threatens a sensible insight into an effect. However, only the probability of effectiveness without a context does not provide the public any meaningful guidelines, as we saw at 2024 YR4.
Sticking and waiting for further data to refine a collision forecast or to introduce new metrics to evaluate the effects on earth are alternative measures to give people better guidelines for future threats before adding confusion and fear.
This article will be released from the conversation, a non -profit, independent news organization that brings you facts and trustworthy analyzes to help you understand our complex world. It was written by: Toshi Hirabayashi, Georgia Institute of Technology
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I studied planetary defense, in particular part of the past, ongoing and future small body missions. I was part of the NASA/DART mission. I am currently part of NASA/Lucy Mission and the ESA/HERA mission. I am also part of international cooperation I have no belonging to Jaxa.
