'City killer' asteroid 2024 YR4 could collide with the Moon

Illustration of asteroid colliding with Earth - Photo: HINDUS TIMES

According to LiveScience on March 31, James Webb has just completed the first observation of the "city killer" 2024 YR4 in 2025 before this asteroid flies further out of the solar system in the next few years.

2024 YR4 is forecast to make a close approach to Earth and the Moon in December 2032.

Asteroid larger than estimated

During the March 26 observation, James Webb observed asteroid 2024 YR4 every 20 minutes for five hours. With the new data, the observing team estimated the asteroid to be wider than previously calculated, about 60 meters.

They also found that the asteroid was cooler than previous objects of similar size, so it had more rocks than studies done with ground-based telescopes.

Fortunately, James Webb still confirms similar to the US Aeronautics and Space Administration (NASA) that 2024 YR4 is no longer dangerous, and the possibility of this asteroid colliding with Earth in 2032 is 0%.

However, the team of astronomers said there is still a nearly 2% chance of a direct collision between 2024 YR4 and the Moon in December 2032.

It sounds scary, but in fact, the Moon is hit by thousands of small asteroids every year, leaving countless dents on the surface of the "Mother Moon". The collision (if any) may leave more scars, but it will give astronomers an opportunity to study the impact of asteroids on the Moon.

A second observation of 2024 YR4 is scheduled for May 2025, which should further improve estimates of its orbit and collision probability.

Why is 2024 YR4 called a "city killer"?

2024 YR4 was first discovered in December 2024. Initial observations measured the asteroid's diameter at about 55m, about as wide as the Leaning Tower of Pisa (Italy) is tall.

2024 YR4's orbit often intersects Earth's orbit around the Sun, so it has a chance of colliding with our planet. If this were to happen, 2024 YR4 would have the power to flatten a city with the force of 500 atomic bombs dropped on the Japanese city of Hiroshima. This is also why 2024 YR4 is called a "city killer".

When analyzing the initial trajectory of asteroid 2024 YR4, researchers estimated that it had a 3.1% chance of colliding with Earth in 2032—the highest impact probability ever recorded for an object of its size. NASA eventually refined that prediction to 0%.

However, the European Space Agency (ESA) noted that James Webb's observations may have errors in the asteroid's estimated size and orbit.

Key to James Webb's asteroid observations are infrared sensors, which directly detect the heat emitted by the asteroid and provide detailed information about its size and composition. Meanwhile, ground-based telescopes can observe the brightness of sunlight reflected from the asteroid's surface.

"In general, the brighter the asteroid, the larger it is, but this relationship depends a lot on the reflectivity of the asteroid's surface. 2024 YR4 could be 40m wide and very bright, or it could be 90m wide but not very reflective. The danger of a 40m wide asteroid is very different from a 90m asteroid," ESA said.

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Source: https://tuoitre.vn/tieu-hanh-tinh-sat-thu-thanh-pho-2024-yr4-co-the-va-cham-mat-trang-20250401122816242.htm