Faced with the (very low probability) threat of a collision with an approaching asteroid, NASA is pulling out the big guns. The agency will use its powerful Webb Space Telescope to observe the recently discovered asteroid 2024 YR4, which has a small probability of colliding with Earth in 2032.
According to current estimates, the probability of asteroid 2024 YR4 colliding with the Earth on December 22, 2032 is 2.1%. While the odds are still on our side, there are currently no other known large asteroids with a collision probability above 1%, according to NASA. The space agency tends to take these issues quite seriously, which is why it plans to collect additional observations of the space rock using the Webb Space Telescope in March to refine current estimates, NASA said in a recent update.
The Asteroid Impactor Last Alert System (ATLAS) in Chile detected the asteroid on December 27, 2024. Shortly after the discovery, the probability of an asteroid colliding with the Earth was set at 1.3%. However, additional observations have increased the probability of an asteroid colliding with the Earth to 2.3% as of yesterday, and this morning it has slightly decreased to 2.1%. These chances are preliminary, and further observations of the asteroid are essential.
When it was first spotted, asteroid 2024 YR4 was at a distance of 515,116 miles (829,000 kilometers) from Earth. Unfortunately, the space rock is moving away from us, and its next close approach will not occur until December 2028. Ground-based telescopes of the International Asteroid Warning Network are currently tracking the asteroid and will continue to do so until April. After that, according to NASA, it will be too faint to observe until June 2028. That’s why Webb will intervene in this process by capturing the asteroid from space.
Using Webb’s observations, astronomers hope to get a better estimate of the asteroid’s size, among many other variables. Current estimates based on reflected light put the asteroid at 130 to 300 feet (40 to 90 meters) wide. It is not large enough to cause complete destruction, but its unlikely impact would release about 8 megatons of energy – more than 500 times the energy released by the atomic bomb dropped on Hiroshima in 1945 and comparable to the energy released in the 1908 Tunguska explosion, according to NASA.
NASA considers any asteroid to be potentially dangerous if its diameter is between 100 and 165 (30 and 50 meters) and if its orbit is within 5 million miles (8 million kilometers) of Earth’s orbit. Asteroid 2024 YR4 topped NASA’s Sentry risk list, which includes all known near-Earth asteroids that have a non-zero probability of colliding with Earth in the future. Currently, it is the only known asteroid with a score of 3 on the Turin Impact Hazard Scale), which NASA defines as “noteworthy for astronomers.”
Several objects in history have risen to the risk list, but then fallen off it as new data emerged, NASA explains in an updated statement, adding: “New observations may lead to the reassignment of this asteroid to 0 as more data becomes available.” Well, let’s hope so.
