A newly discovered asteroid — called 2024 YR4 — has slightly more than 1% chance of crashing into Earth in 2032, National Aeronautics and Space Administration (NASA) officials said last week. In a statement, Paul Chodas, director of NASA’s Center for Near Earth Object Studies, said, “We are not worried at all, because of this 99 percent chance it will miss… But it deserves attention.” Here is a look at the 2024 YR4, how much destruction it can cause if it crashes into Earth, how often asteroids crash into Earth, and how space agencies are trying to deal with such situations. What is the newly discovered asteroid 2024 YR4? The 2024 YR4 was first discovered in December last year by a telescope in Chile. The near-Earth asteroid is as big as a football field, measuring 40 to 100 metres across. It came closest to Earth on Christmas Day — passing within roughly 800,000 kilometres of Earth, about twice the distance of the moon, according to a report by the Associated Press. It will eventually fade from view over the next few months, and will not be visible again until it passes Earth’s way again in 2028. That is why scientists across the world are currently busy using some of the most powerful telescopes to determine 2024 YR4’s path and size before it gets out of sight. To do so, scientists have until mid-April when the asteroid will become too faint to detect. To check how large an asteroid is, astronomers examine the brightness of the object — brighter objects are bigger. However, it is difficult to tell the exact measurements as the brightness depends on how reflective the asteroid’s surface is (asteroids do not emit a light of their own, they only reflect sunlight). As a result, it is a challenge to distinguish between a large, dark-colored asteroid and a small, highly reflective one. How much destruction could the 2024 YR4 cause? Experts said the 2024 YR4 is big but not as big as the asteroid that wiped out dinosaurs and most other extant life some 66 million years ago. The 2024 YR4, however, can cause considerable localised damage in case it hits a populated area. Astronomers use something called the Torino Scale to categorise an object’s destruction potential. The NASA JPL Center for Near-Earth Object Studies (CNEOS) has currently rated the 2024 YR4 a 3 on a scale from 0 to 10. Apophis asteroid, which was discovered in 2004, was initially rated 4 on the scale but was later downgraded as observations showed that it posed no threat for at least 100 years. The 2024 YR4 is expected to release 8 to 10 megatons of energy in case of a crash, according to scientists. The asteroid that hit Chelyabinsk, Russia, on February 15, 2013, released energy equivalent to about 500 kilotons of TNT — about 30 times more than the Hiroshima atomic bomb, according to a report by NPR. It injured around 1,500 people and caused damage to thousands of buildings across several cities. That asteroid was around half the size of 2024 YR4. How often do asteroids crash into Earth? Thousands of asteroids enter the Earth’s atmosphere every day. Most are very small and burn up in the atmosphere due to friction — some of the larger ones burn spectacularly, and show up as fireballs in the sky. Sometimes unburnt fragments hit the surface but they are not big enough to cause much damage. Large asteroids, which can cause global disasters, hit Earth much less often. Those bigger than a kilometre in diameter, such as the Chicxulub asteroid that sent the dinosaurs into extinction might hit in 260 million years, according to a report by DW. That is because our Solar System is huge compared to the size of Earth, which means that the chance that the Earth will be hit by an object such as an asteroid is very small. But smaller asteroids can also cause damage, like the one did in Chelyabinsk. It all depends on the asteroid's speed and angle of entry into Earth’s atmosphere. A 40-metre-wide rock could level an entire city, the DW report said. How do space agencies plan to avert possible asteroid crashes? Space agencies such as NASA are as of now working on planetary defence mechanisms that can prevent celestial bodies from colliding with Earth with potentially catastrophic consequences. For instance, the Double Asteroid Redirection Test (DART), a joint project between NASA and the Johns Hopkins Applied Physics Laboratory, was the first planetary defence mission of NASA. In 2022, a DART spacecraft crashed an asteroid named Dimorphos, and successfully changed both its shape and its trajectory. Dimorphos did not pose a threat to Earth, and was circling the Sun some 11 million kilometres away from the planet.
