Odds of impact increased yet again
As of midday by American clocks on February 18, 2025, we are now up to a 3.1% – or 1-in-32 odds – of asteroid 2024 YR4 hitting Earth on December 22, 2032. The odds have gone up steadily as astronomers have aimed their telescopes at this asteroid, and gathered more measurements of the space rock’s movement around the sun. Those measurements enable astronomers to refine the asteroid’s orbit. Not long after 2024 YR4’s discovery – in late 2024 – astronomers were saying there was a 1-in-83 chance of a strike. Then the odds went to 1-in-53, and then 1-in-43. Just yesterday we heard there was a 1-in-38 chance of a strike. Today, the number has jumped up again to 1 in 32.
Don’t be afraid. It’s still likely that the odds will go down to zero with further data. But it might take a while to get that data. This small asteroid asteroid is faint and getting fainter. It’s getting harder to acquire measurements of its orbit. After another month or so, astronomers won’t be able to track it again until 2028.
Asteroid 2024 YR4 is 50 million miles (80 million km) away and getting farther every second. Some observers noticed the asteroid will be somewhat “close” to the Lucy spacecraft, so its team checked to see if 2024 YR4 would be observable by the spacecraft. But – at its closest to Lucy – the asteroid will still be too faint for the spacecraft’s L’LORRI instrument to detect.
Despite the increased odds of the asteroid striking Earth, asteroid 2024 YR4 still sits at a 3 on the Torino Impact Hazard Scale. That’s not a hugely high risk of strike. But it’s still higher than any asteroid has been before.
The previous record-holder was the infamous asteroid Apophis at 2.7% in 2004. And, according to asteroid expert Richard Binzel of MIT – who we interviewed on our livestream in late January 2025 – the odds are very likely to go to zero, eventually.
Meanwhile, the new estimates for 2024 YR4 come from NASA’s Center for Near Earth Object Studies (CNEOS) at the Jet Propulsion Laboratory in Pasadena, California.
Why do the odds keep going up?
The more measurements astronomers can make of the asteroid’s orbit, the more they can refine the uncertainty. So, imagine a wide highway passing between Earth and the moon. More observations shrink that highway, including away from the farther side from Earth (near the moon), so technically it’s odds of being closer to us go up.
Speaking of the moon … scientists have also calculated the odds of the asteroid hitting the moon. It’s smaller than the odds of Earth, at only 0.3%, but what a sight that would be!
Where could asteroid 2024 YR4 hit?
Just to reiterate, it’s most likely that this asteroid WILL NOT HIT Earth. But, what everyone’s wondering is, if it did, where would it hit? Here’s the best idea we have of location at this point:
Here are 70 clones of #asteroid 2024 YR4 that do hit Earth, highlighting the impact risk corridor. There are some big cities along that line: #Bogota, #Lagos, #Mumbai.
— Tony Dunn (@tony873004.bsky.social) February 10, 2025 at 1:08 PM
— Tony Dunn (@tony873004.bsky.social) February 10, 2025 at 2:56 PM
Asteroid 2024 YR4 discovered on Christmas Day, 2024
Asteroid 2024 YR4 swept into the view of the ATLAS asteroid impact early warning system – with telescopes in Hawaii, Chile and South Africa – on December 25, 2024. Back on January 27, 2025, the space rock had 1-in-83 odds of hitting Earth in 2032. Those odds have since increased slightly. The asteroid is about 150 feet (46 meters) wide. The International Astronomical Union (IAU) keeps what it calls the Torino Impact Hazard Scale to rate the risk of asteroids making close encounters with Earth. Asteroid 2024 YR4 has a current value of 3 on the Torino scale. At this time, it is the only asteroid with a value above 1 or 0.
EarthSky spoke with the inventor of the Torino scale, Richard Binzel of the Massachusetts Institute of Technology (MIT), yesterday (January 27, 2025). He said:
In all likelihood, this object will fall to Torino Scale 1 and then 0; or directly fall to 0 with more measurements.
2/ The clip below shows ESO’s VLT recent observations of asteroid 2024 YR4, which have helped refine its trajectory. It is estimated to be 40-100 m wide, but more data and analysis are needed to confirm the size, and to refine its trajectory. ? ?
? ESO/O. Hainaut et al.
— ESO (@eso.org) January 29, 2025 at 11:01 AM
The Torino rating can change
The only asteroid ever to have a higher score on the Torino scale was 99942 Apophis. It briefly had a rating of 4 on the Torino Scale in late 2004. And, yes, Apophis caused a stir and earned the nickname of the Doomsday Asteroid. But asteroid Apophis is now just a zero on the Torino scale. That’s because astronomers watched it carefully, refining their knowledge of its orbit. They determined that Apophis has a negligible risk of impact for at least a century.
So, yes, an asteroid’s score on the Torino scale can change – in fact, is likely to change – as astronomers gather more observations of the object and also track its motion around the sun.
If asteroid 2024 YR4 were to strike Earth, it wouldn’t end life on Earth as we know it. It’s not large enough to do that. But it could be locally destructive, depending on where it hit (IF it hits). Watch a video of size comparisons in asteroids, here.
So asteroid 2024 YR4 isn’t a world-destroyer. Instead, it’s thought to be similar in size to the object that felled reindeer and flattened some 1,000 square miles (2,600 square km) of forest, in a sparsely populated area near Tunguska, Siberia, in 1908.
What is the Torino scale?
The IAU has been using the Torino Impact Hazard Scale since 1999 to categorize asteroids that could potentially hit Earth. An object – such as 2024 YR4 – with a score of 3 puts it in the yellow zone. This means the object merits attention by astronomers and the public. The description of a score of 3 reads:
A close encounter, meriting attention by astronomers. Current calculations give a 1% or greater chance of collision capable of localized destruction. Most likely, new telescopic observations will lead to reassignment to Level 0. Attention by public and by public officials is merited if the encounter is less than a decade away.
In fact, most new asteroids that get listed on the Torino scale have their likelihood of hitting Earth go up with more observations … until it drops to zero. That’s because the uncertain path of the asteroid is wide and more observations shrinks the path, making it look more likely, until the path shrinks enough to show that it will not cross Earth’s. It’s likely that’s what will happen with asteroid 2024 YR4 also.
In 2023, EarthSky spoke with the inventor of the Torino scale, Richard Binzel of the Massachusetts Institute of Technology. He said that we should expect more objects to make the Torino scale as our technology improves, allowing us to see smaller objects we otherwise would have missed.
So, we had better get used to seeing objects on the Torino scale, at least temporarily.
EarthSky’s Deborah Byrd interviewed asteroid expert Dr. Richard Binzel of MIT – inventor of the Torino Scale – about asteroid 2024 YR4.
Asteroid Potential Impact Warning Notification
Because the asteroid passed a slim threshold of hitting Earth, it triggered a Potential Impact Warning Notification on January 29, 2025. That warning came from the International Asteroid Warning Network, a global collaboration of observatories, scientific institutions, and other interested parties, coordinated by NASA.
On January 29, the impact probability was a mere 1.3% as calculated by CNEOS and ESA’s Near Earth Objects Coordination Centre in Frascati, Italy, in cooperation with the NEO Dynamic Site (NEODyS-2), also in Italy.
The notice gives the potential date of impact as December 22, 2032, and lists the possible impact locations (from across the eastern Pacific, northern South America, into Africa and southern Asia). Because it’s currently so dim and far away, size estimates vary from between 130 to 300 feet (40 to 90 m). If it were to strike Earth, it would cause “severe blast damage.” Specifically, the blast damage could occur as far as 30 miles (50 km) from the site of impact. And finally, the notice said:
The asteroid will be observable, and information will be updated, through early April 2025 and then again starting in June 2028 when the asteroid will return to the vicinity of Earth.
So it might be a while before we get the all clear!
Asteroid 2024 YR4 presents a challenge
Asteroid 2024 YR4 presents a challenge to observations, however. The potential for an impact is still seven years away, but the asteroid is moving into a position where astronomers will not be able to observe it for about three years. At the moment, the asteroid is exceedingly faint at magnitude 23. It is expected to continue to dim throughout February until it leaves our view.
Will we get enough observations of asteroid 2024 YR4 to be able to remove it from where it currently sits on the Torino scale? There’s no way to know that at this time.
With the current data astronomers have on the asteroid, they estimate not just one possibility for impact in 2032, but seven possibilities between 2032 and 2079. The first possible impact date is December 22, 2032. Again, as more observations come in, this information will change.
Future observations
So, what if further observations of asteroid 2024 YR4 determine that it is on a collision course with Earth on December 22, 2032? To start with, the first potential impact is still years away. And we’ve already sent a mission to hit and move an asteroid as a test of our planetary defense system. That mission was the Double Asteroid Redirection Test (DART), which impacted with an asteroid’s moon named Dimorphos in 2022.
And Dimorphos was much larger than asteroid 2024 YR4, at 525 feet (160 meters) across.
If it’s determined that asteroid 2024 YR4 will strike Earth, we are (at least somewhat) prepared!
Bottom line: On February 18, 2025, new observations of asteroid 2024 YR4 have led NASA’s Center for Near Earth Object Studies to slightly increase the odds of the asteroid hitting us in 2032 to 1 in 32.
Via:
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