Recently, headlines have been dominated by the alarming news that a massive asteroid has a high chance of striking the Earth in 2032. Discovered in December of 2024 and accordingly named 2024 YR4, this 100-meter-wide asteroid is the current focal point of global space agencies. In February, NASA estimated that this space rock has a 3.1% probability of hitting the Earth. This surpassed the 2.7% chance of collision calculated for the asteroid Apophis in 2004, thus making it the most dangerous asteroid to be detected by the human race. Moreover, according to NASA, the asteroid far exceeds the threshold for alerting the US government agencies responsible for planetary defense, which is anything above a 1% chance.
In response to this new discovery, NASA is utilizing the Asteroid Terrestrial-impact Last Alert System (ATLAS) to track the asteroid. Telescopes stationed all across the globe have been instructed to monitor the threat, including the James Webb Telescope, which is currently wandering the depths of space. Since January, scientists have been using the Very Large Telescope in Chile, the Magdalena Ridge Observatory in New Mexico, and the Danish Telescope to pin down the asteroid. Unfortunately, the asteroid will leave our sight this month to complete its four-year journey around the sun, preventing our ability to observe it for a while.
Scientists have estimated the potential impact of 2024 YR4 using the Torino impact hazard scale. Invented by Richard Binzel, a professor of planetary science at Massachusetts Institute of Technology, this scale is an index system that provides a clear and understandable measurement of the riskiness of collisions. 2024 YR4 is ranked 3 on the scale, making it the only asteroid other than Apophis to yield a ranking greater than 0. While its ranking is slightly lower than Apophis due to its smaller size, any asteroid greater than 20 meters in width can cause considerable damage. In 2013, a 20-meter-wide asteroid exploded in the air as it entered the atmosphere, releasing 30 times the energy of the first atomic bomb. The explosion injured more than 1000 people and damaged 7000 buildings in Chelyabinsk, Russia. 2024 YR4 is estimated to be 5 times larger than the 20-meter-wide asteroid and has the potential to cause even greater damage.
Currently, scientists are attempting to resolve the uncertainty over the asteroid’s orbit and how close its trajectory will be to Earth. To explain the unpredictability of 2024 YR4’s orbit, Binzel compares it to an extra-long fettuccine noodle that stretches across the path of the moon around the Earth. “Earth just happens to lay underneath that noodle, and the fraction that the Earth occupies is the probability of impact,” Binzel explained, “More data on the asteroid shrinks the noodle.” However, tracking this asteroid is challenging because it is small in size and moving away at a fast rate. “While certainty for 2024 YR4 missing the Earth is the outcome we expect, it’s not up to us. It’s for nature to decide,” Binzel concluded. “In fact, nature already has settled the question. We just don’t know that answer yet.”