Subscribe to CNN’s Wonder Theory science newsletter for insights into the cosmos. Stay updated on intriguing discoveries, scientific progress, and much more!

CNN
 — 

Recently, astronomers have identified an asteroid named 2024 YR4 as the most perilous asteroid ever recognized. On Tuesday, NASA assessed the likelihood of this celestial body impacting Earth in 2032 at approximately 3.1%, while the European Space Agency determined a slightly lower risk estimate of 2.8%.

The variation in these figures arises from the distinct methodologies employed by each agency in tracking the asteroid’s trajectory and evaluating its potential collision risk. Nevertheless, both agencies’ probabilities exceed the previous 2.7% collision risk associated with the asteroid Apophis, discovered in 2004, making 2024 YR4 the most critical asteroid identified in the last twenty years.

Moreover, a recent update from NASA revealed that the impact probability for December 2032 has been revised to 1.5%, following updated observations post full moon phase. Experts anticipate such adjustments as more observational data is collected.

Measuring approximately 1,148 feet (350 meters) in diameter, Apophis was earlier regarded as one of Earth’s most dangerous asteroids, previously rated a 4 out of 10 on the Torino Impact Hazard Scale, designed to categorize the impact risks of space objects. This assessment warranted continuous monitoring by astronomers, which was later adjusted in 2021 based on more accurate orbit data.

Experts anticipate similar predictions for 2024 YR4, which currently holds a level 3 on the Torino Scale and is estimated to range from 131 to 295 feet (40 to 90 meters) wide—comparable to the height of a substantial building.

“Among asteroids larger than 30 meters, 2024 YR4 has now surpassed all others for the highest recorded probability of impact and the longest duration for staying above a 1% impact likelihood,” stated the ESA.

“It’s essential to understand that this increasing probability of impact is a normal outcome as we refine our understanding of the asteroid’s orbit. As more observations accumulate, the uncertainty in projections decreases, and while the impact probability may increase in the interim, it will plummet to zero if the data eventually indicates Earth is outside the risk zone.”

Astronomers are employing a variety of telescopes to investigate the asteroid’s dimensions and trajectory, which is expected to ultimately reveal lower prospects for a collision with Earth in 2032 than currently projected.

Apophis reached its ranking of 4 on the Torino Scale due to its capacity for causing regional devastation, while 2024 YR4 is rated a 3 because its impact would likely result in localized damage, according to Richard Binzel, the creator of the scale.

Binzel introduced his Torino Scale concept at a 1995 United Nations forum, which was later endorsed by a working group from the International Astronomical Union during a meeting in Torino, Italy, and subsequently published in 1999. He emphasized the need for a systematic method to evaluate the risks posed by near-Earth objects as they became more observable thanks to improved asteroid screening technologies.

“The uncertainties surrounding the preliminary orbits of many of these objects can lead to calculations indicating a non-zero probability of collision over the upcoming century,” Binzel noted in his 1999 paper. “This proposed index system gives clarity to the hazard posed by close approaches, enabling straightforward communication between scientists and the general public.”

According to the Torino Scale, a ranking of 3 for 2024 YR4 means that “current assessments indicate a 1% or higher chance of collision with potential for localized destruction. It is likely that further telescopic observations will lead to a reassignment to Level 0. Public interest and attention from officials are warranted if an encounter is anticipated within the next decade.”

Binzel added that it’s quite natural for impact probabilities to fluctuate before diminishing to zero.

Some of the uncertainty stems from determining 2024 YR4’s orbital path and its proximity to Earth in future encounters. Astronomers are only beginning to measure this asteroid’s four-year solar orbit, making long-term predictions challenging.

Although it is expected that 2024 YR4 will pass by Earth safely, much like Apophis is anticipated to do in 2029 (when several spacecraft plan to observe it), it remains crucial for astronomers to diligently monitor and gather data on the asteroid, and Binzel confirms that the scientific community is actively engaged in this effort.

Using a pasta metaphor in tribute to the Italian origin of the scale, Binzel likened the uncertainty surrounding the asteroid’s future trajectory to the stretch of a fettuccine noodle that crosses the lunar orbit around Earth.

“The Earth just happens to fall under that noodle, and the portion that Earth covers represents the impact probability,” Binzel explained in an email. “In gathering more information about the asteroid, we narrow the noodle’s diameter. As this narrows but still encompasses Earth, the calculated impact likelihood can increase. Eventually, we will pinpoint the asteroid’s position to that of a single grain, which will likely not align with Earth’s position—it could even be farther than the Moon.”

The asteroid was identified after a close pass by Earth in December, and it won’t be visible again until June 2028 after its next flight past our planet.

“At its farthest reach, YR4 will approach near Jupiter’s orbit,” Binzel noted. “YR4 poses a challenge as it is small and moving away from Earth. Local telescopes can track it for the next few months, after which we will employ (the James Webb Space Telescope) if further tracking is necessary.”

The Webb telescope is anticipated to start observing the asteroid in March, aiding astronomers in accurately determining its orbit and dimensions.

“While we are optimistic that 2024 YR4 will miss Earth, the final outcome is ultimately beyond our control—it’s for nature to decide,” Binzel remarked. “Indeed, nature has likely already resolved this matter; we just have to wait to uncover the answer. This is why ongoing tracking efforts are so crucial.”