An asteroid ranging from 130 to 300 feet in diameter is currently under scrutiny for a potential collision with Earth in 2032. However, the exact likelihood of this event has been fluctuating since the celestial object was initially detected nearly two months ago.
The latest assessment from NASA concerning the asteroid, designated as 2024 YR4, indicates a mere 0.28% chance of impacting Earth — roughly 1 in 360 odds. Contrastingly, just a day earlier, NASA had estimated a significantly higher probability of 3.1%, equating to a 1 in 32 chance of a collision occurring.
These previous calculations elevated the space rock to a Level 3 classification on the Torino scale, a hazard measurement system introduced by astronomer Richard Binzel nearly thirty years ago. A Level 3 rating signifies that the object warrants close observation due to the potential risk it poses.
Originating from the Italian city that officially adopted it in 1999, the Torino Impact Hazard Scale employs color-coded categories ranging from 0 (white indicating no threat) to 10 (red indicating an imminent collision). At the time of the 3.1% impact probability, asteroid 2024 YR4 fell into the intermediate yellow zone on the scale.
The recent surge in news coverage surrounding the asteroid has brought unprecedented attention to the Torino scale. Binzel emphasized that this surge validates the original purpose of creating the system – to ensure transparency in conveying the known risks to the public.
Despite the dynamic shifts in impact probabilities, it is a common occurrence for near-Earth asteroids to exhibit such variability. Binzel likened the situation to predicting the landing spot of a fly ball in baseball, highlighting the challenges in accurately determining the asteroid’s threat level.
Asteroid 2024 YR4 is estimated to have a diameter of up to 300 feet. Binzel’s intention in introducing the Torino scale was to enhance public awareness of potential impact hazards, drawing parallels to established scales like the Richter scale for earthquakes or the Saffir-Simpson scale for hurricanes based on their intensity.
During a United Nations conference in 1997, a proposal was made that did not receive a warm reception, as noted by a speaker. Astronomers, as relayed by Binzel, expressed skepticism about its potential usefulness for the general public. In the same year, however, a significant discovery was made by scientists – an asteroid named 1997 XF11, which raised concerns about a possible impact on Earth in 2028. Although astronomers quickly ruled out the likelihood of a collision, the doomsday scenario gained traction in media reports, leading to criticism over what appeared to be a major oversight. Binzel reflected on this episode, admitting it turned into a somewhat embarrassing situation. He emphasized that the issue wasn’t a mistake on the part of astronomers, but rather a lack of effective communication regarding uncertainty. This served as the catalyst for the proposal of a straightforward system to classify objects that could potentially come into contact with Earth in the distant future.
Subsequently, Binzel reintroduced this classification scale at a conference in Torino in 1999, attended by representatives from NASA and the European Space Agency. It was at this event that the system was officially adopted by the International Astronomical Union, a professional organization comprising astronomers that serves as a governing body within the astronomical community. In addition to utilizing colors and numerical values to indicate different levels of risk, the scale also provides information on potential consequences, the likelihood of revised risk assessments, and recommended actions for governments and the public.
For instance, a Level 6 threat in the orange zone denotes a scenario where a large object poses a serious but uncertain risk of a global catastrophe. Astronomers are urged to closely monitor such objects to determine definitively whether a collision is imminent. If the projected encounter is within three decades, the scale suggests that governmental contingency planning may be necessary. On the other hand, a Level 3 threat signifies a 1% or greater chance of a collision capable of localized destruction, with the expectation that updated observations may lead to reclassification to a lower threat level. The public and public officials are advised to pay attention if the projected encounter is less than ten years away.
Predictably, Binzel correctly predicted that asteroid 2024 YR4, initially classified as a Level 3 threat, would eventually be downgraded. However, during its brief stint at the higher threat level, 2024 YR4 achieved notable milestones, including being the sole asteroid ranked above Level 1 and setting records for the highest impact probability and the longest duration of a probability exceeding 1%, as reported by the European Space Agency. The only other asteroid of similar or larger size to receive a higher ranking on the Torino scale was Apophis in 2004, briefly classified as a Level 4 threat with an estimated 2.7% chance of impact.
Binzel expressed satisfaction in witnessing the Torino scale in action in real-time, albeit preferring to maintain anonymity in connection to its development. He acknowledged the
