UN planetary defense groups are tracking an asteroid named YR4, which has a slim risk of striking Earth. The European Space Agency (ESA) reports that YR4 has a 99% chance of safely passing Earth on December 22, 2032. However, there remains a 1.3% possibility of an impact, which “cannot yet be completely ruled out.”
Dr. Robert Massey of the Royal Astronomical Society reassures the public, saying, “There is no need for alarm.” He explains that when initial calculations suggest a potential impact, probabilities typically drop to zero with further observations. Massey emphasizes the importance of providing astronomers with resources to track such objects and take timely action.
The asteroid, discovered on December 27, 2024, measures between 40 and 90 meters across. If it struck Earth, YR4 could unleash the force of a nuclear bomb, causing significant damage in populated areas. Fortunately, experts believe it would more likely hit the ocean or a remote region. Its exact impact location remains uncertain due to its distance and current lack of precise data.
Asteroid Monitoring and Next Steps
Since early January, astronomers have refined their measurements of YR4’s size and path. On the Torino Impact Hazard Scale, YR4 is now ranked 3 out of 10, indicating a close encounter worth monitoring. Only levels 8 to 10 represent a confirmed and highly destructive collision.
History has shown that these risks often decrease with time. For example, in 2004, astronomers initially calculated a 2.7% chance of asteroid Apophis striking Earth in 2029. Subsequent observations ruled out the threat entirely.
When an asteroid over 50 meters wide poses a greater than 1% impact risk, precautionary protocols are activated. These include launching two UN-endorsed response teams: the International Asteroid Warning Network (IAWN), led by NASA, and the Space Mission Planning Advisory Group (SMPAG), chaired by the ESA.
The SMPAG is meeting this week to decide on further actions. While no immediate measures are planned, the group will continue monitoring the asteroid’s potential threat. Future discussions are scheduled for April or May unless developments require earlier action. If YR4’s risk remains above 1%, SMPAG will advise the UN and explore possible interventions.
If necessary, one strategy could involve deflecting the asteroid by colliding it with a robotic spacecraft. NASA demonstrated this with the DART mission in 2022, successfully altering the trajectory of a non-threatening asteroid. Dr. Massey affirms that this technique is effective but relies on early detection.
Currently, YR4 is moving away from Earth in a nearly straight line, making its exact orbit hard to calculate. In the coming months, it will fade from view but will continue to be tracked by both ground and space telescopes. ESA notes that if the asteroid becomes unobservable before a zero-risk determination is made, it may remain on the agency’s risk list until its return in 2028.