At the time of writing, the odds of asteroid 2024 YR4 hitting Earth are 1 in 20,000. (Image credit: Eric Simonsen via Getty Images)
A record-sized asteroid that could destroy an entire city in 2032 is no longer considered a threat, according to the latest information from NASA.
Last week, NASA raised the odds of asteroid 2024 YR4 impacting to 1 in 32, or 3.1%, up from 1.2% in early February. 2024 YR4 is big enough to wipe out a major city, and with a 3.1% impact probability, it had the highest impact probability ever recorded by NASA for an object of its size or larger. People naturally took notice, but don’t worry.
The chance of a collision soon dropped as the space agency learned more about 2024 YR4's trajectory. By Friday (Feb. 21), 2024 YR4 had a 1 in 360, or 0.28%, chance of a collision, and that chance continued to increase over the weekend.
At the time of writing on Monday (Feb. 24), the odds were 1 in 20,000, or 0.005%, according to NASA's Center for Near-Earth Object Studies. This latest change is significant because now that the odds have dropped below 1 in 1,000, NASA has lowered the threat level of 2024 YR4 to the lowest possible (level 0 on the Torino Impact Hazard Scale).
This latest redistribution was predicted with high probability. Live Science previously reported that the most likely scenario was always that 2024 YR4 would pass us by during its closest approach to Earth on December 22, 2032.
Astronomers discovered 2024 YR4 last December, which explains its name. The asteroid is about 180 feet (55 meters) in diameter, which is about the width of the Leaning Tower of Pisa. If 2024 YR4 were to hit Earth in seven years, it would release about 8 megatons of energy — more than 500 times more than the atomic bomb that destroyed Hiroshima.
Astronomers use the Torino scale to assess the risk posed by asteroids and comets. When 2024 YR4 surpassed a 1% chance of impact in January, the asteroid was classified as a Level 3 on the Torino scale, meaning it could cause “localized destruction” and warrants attention, according to the scale. By the end of last week, 2024 YR4 had dropped to a Level 1 (an unusual level of danger) as the chance fell below 1%. Now, with the latest drop, 2024 YR4 has reached the lowest level on the scale.
“Asteroid 2024 YR4 is now assigned a Torino scale level of 0 (the 'safe' level) because further tracking of its orbital trajectory reduces its probability of crossing Earth to below the 1 in 1,000 required for a downgrade to level 0,” Richard Binzel, the creator of the Torino scale and a professor of planetary science at MIT, told Live Science in an email.
The Torino scale is based on both the impact consequences, determined by the asteroid's size, and the impact probability. Binzel noted that a probability of less than 1 in 1,000 is the Level 0 threshold for any object smaller than 100 m (330 ft), which is the case for the projected 55-meter (185 ft) 2024 YR4.
“NASA's JPL Center for Near-Earth Object Studies now estimates the probability of 2024 YR4 as 0.00005 (0.005 percent), or 1 in 20,000, passing by Earth in 2032,” Binzel said. “That's zero, guys!”
Following the downgrade of this space object, there is currently no known asteroid with a threat level greater than zero.
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