A "potentially hazardous" asteroid the size of a blue whale is set to zip past Earth on Friday (Aug. 12), according to NASA (opens in new tab).
The asteroid, named 2015 FF, has an estimated diameter between 42 and 92 feet (13 and 28 meters), or about the body length of an adult blue whale (Balaenoptera musculus), and it will zoom past the Earth at 20,512 mph (33,012 km/h).
At its closest approach, the asteroid — traveling at around than 27 times the speed of sound — will come within about 2.67 million miles (4.3 million kilometers) of Earth, a little more than eight times the average distance between Earth and the moon. By cosmic standards, this is a tiny margin.
NASA flags any space object that comes within 120 million miles (193 million km) of Earth as a "near-Earth object" and any fast-moving object within 4.65 million miles (7.5 million km) is categorized as "potentially hazardous." Once the objects are flagged, astronomers closely monitor them, looking for any deviation from their predicted trajectories — such as an unexpected bounce off another asteroid — that could put them on a devastating collision course with Earth.
NASA knows the location and orbit of roughly 28,000 asteroids, which it maps with the Asteroid Terrestrial-impact Last Alert System (ATLAS) — an array of four telescopes capable of performing a complete scan of the entire night sky once every 24 hours. Since ATLAS came online in 2017, it has detected more than 700 near-Earth asteroids and 66 comets. Two of the asteroids detected by ATLAS, 2019 MO and 2018 LA, actually hit Earth, the former exploding off the southern coast of Puerto Rico and the latter landing near the border of Botswana and South Africa. Fortunately, those asteroids were small and didn’t cause any damage.
NASA has estimated the trajectories of all the near-Earth objects beyond the end of the century, and the good news is that Earth faces no known danger from an apocalyptic asteroid collision for at least the next 100 years, according to NASA.
But this doesn’t mean that space watchers think they should stop looking. Though the majority of near-Earth objects may not be civilization-ending, like the cataclysmic comet that appears in the 2021 satirical disaster movie "Don't Look Up," there are still plenty of devastating asteroid impacts in recent history to justify the continued vigilance.
In March 2021, a bowling ball-sized meteor exploded over Vermont with the force of 440 pounds (200 kilograms) of TNT, Live Science previously reported. Those fireworks, however, have nothing on the most explosive recent meteor event, which occurred near the central Russian city of Chelyabinsk in 2013. As the Chelyabinsk meteor struck the atmosphere, it generated a blast roughly equal to around 400 to 500 kilotons of TNT, or 26 to 33 times the energy released by the Hiroshima bomb. Fireballs rained down over the city and its environs, damaging buildings, smashing windows and injuring approximately 1,200 people.
If astronomers were to ever spy an asteroid careening straight toward our planet, space agencies around the world are already working on possible ways to deflect the object. On Nov. 24, 2021, NASA launched a spacecraft as a part of its Double Asteroid Redirection Test (DART) mission, which plans to redirect the non-hazardous asteroid Dimorphos by ramming it off course in autumn 2022, Live Science previously reported. China is also in the early planning stages of an asteroid-redirect mission. By slamming 23 Long March 5 rockets into the asteroid Bennu, the country hopes to divert the space rock from a potentially catastrophic impact with Earth.
Originally published on Live Science.