What is the possibility that an asteroid will shock Earth in 2032?

Over the next few days in mid-February, headlines all over the world talked about the possibility of an asteroid hitting Earth in 2023. In particular, Asteroid 2024 YR4. The likelihood of this impact rose to a 3.1% high on February 18th.

That number has since dropped to near zero, but the news was a real “no-looking” moment, a harsh reminder of the threat that asteroids pose to life on Earth.

As a planetary geologist, my research focuses on the impact craters of metstones, the scars of the effects of large asteroids and comets of Earth’s past.

It shocks the earth

In our entire solar system there are countless asteroids and an unknown number of comets. Most of these objects date back to the beginning of the solar system around 4.5 billion years ago.

Research has identified around 200 locations where these asteroids or comets have attacked Earth in the past to form impact craters of metstones. It is very rare for a planetary geologist to know if it is a hit asteroid or comet.

One of the most famous of these 200 or so impact craters is the Chicxulub impact crater, 200 km in diameter, on Mexico’s Yucatan Peninsula. This shock wiped out 65% of all species on Earth, including dinosaurs that were 66 million years ago.

One of the most recent and best preserved craters on the planet is the Arizona 1.2 km diameter meteor crater formed 50,000 years ago.

Millions of Craters

The 200 craters over 4.5 billion years do not appear to be a major or cause of concern, but this number is only a small part of the actual record. Most impact craters that form on Earth have been eliminated by plate tectonics, volcanic eruptions, water, wind and ice erosion.

To truly understand how common impact a crater can have, we need to look to the moon, the closest neighbor of the planet. Because of its proximity, objects that could hit the moon could also collide with the Earth. In fact, the Earth is bigger, which means that our gravity is more attractive.

The best estimates are 1.3 million craters over 1 km in diameter of the moon, and a smaller crater of around 700,000.

Calculations have been updated

Asteroid 2024 YR4 was discovered on December 27, 2024 by Chilean station of the Asteroid’s Terrestrial Impact Trastor Alt System (ATLAS). It was soon recognized as a near-earth object (NEO). Additional telescope observations allowed astronomers to better calculate the trajectory.

In January, the chances of the asteroid hitting Earth exceeding 1%, sparking a series of international responses. The International Asteroid Warning Network coordinates telescopes around the world to provide further observations and narrows down uncertainties in their orbit.

On February 18, NASA and the European Space Agency announced that the asteroid 2024 YR4 hit Earth in 2023 had a 3.1% chance, the highest ever recorded for an object of this size. This represents one of the 32 odds. For comparison, the chances of death in a car accident in the US are 1%, or 1% in 95. The possibility that an asteroid would hit the Earth was quite important.

Thankfully, the most recent estimate of the probability of impact approaches zero based on improved calculations of its trajectory.

We’re unhooking…for now.

Potential impact

“If placed on top of Paris, London and New York, it essentially wipes out the entire city and some surrounding area, leading to the asteroid 2024 YR4, known as the “city killer,” said Bruce Betts, the chief planetary scientist of the Planet Society.

The average impact velocity of asteroids on Earth is 17 km per second. This is 25 times faster than the F-35’s lightning strike fighter.

To calculate the mass of an asteroid, you need to know its size. 2024 YR4 estimates are 40-90 meters. Getting the top estimate of 90 m allows you to calculate the energy released at about 9 megatons, equivalent to the explosion energy of 9 million tons of TNT. For comparison, only 0.015 megatons of atomic bombs fell in Hiroshima, Japan in 1945.

The crater formed by this 90 m asteroid is approximately 2.7 km in diameter. This is just over twice the diameter of the meteor crater.

However, the destruction does not stop. Nuclear weapons research suggests that each megaton could destroy around 50 km2, which suggests that the impact could destroy up to 450 km2 around the crater via fireballs, supersonic ejedas and earthquake shaking.

As some reports suggested, is this a city murderer? absolutely. The urban area is 232 km2 and my hometown of Ontario, Ontario, in London, will completely destroy around 420,000 people.

Actual risks

The good news is that we estimate that the effect of an asteroid with a diameter of 90 m occurs once every 10,000 years. For asteroids of the size of 40 m, this drops once every 1,000 years, but the destructive effects are dramatically reduced. It is worth pointing out that these numbers are very approximate and will not help us understand when the next number will happen.

As the story about Asteroid 2024 YR4 shows, there is good news that asteroid detection is getting better. Thanks to the coordination of the United Nations Office for Space and Space Issues, many space agencies around the world are working together and have the knowledge that this is our whole Earth problem.

If the calculations continued to make sure that the asteroid 2024 YR4 was likely to hit Earth in 2032 and there was sufficient time, then attempts to deflect the asteroid could have been attempted. In September 2022, NASA’s Dart Spacecraft provided the first demonstration that it is possible to divert an asteroid from its path. This was imagined in Hollywood movies, but has not been proven to be impossible until then.

This article will be republished from the conversation under a Creative Commons license. Please read the original article.