This asteroid might collide with Earth in 2032

On 27 December last year, astronomers using the ATLAS survey telescope in Chile discovered a small asteroid moving away from Earth. Follow up observations have revealed that the asteroid, 2024 YR4, is on a path that might lead to a collision with our planet on 22 December 2032

Queensland: On 27 December last year, astronomers using the ATLAS survey telescope in Chile discovered a small asteroid moving away from Earth. Follow up observations have revealed that the asteroid, 2024 YR4, is on a path that might lead to a collision with our planet on 22 December 2032. In other words, the newly-discovered space rock poses a significant impact threat to our planet.

What do we know about 2024 YR4? And what would happen if it did collide with Earth?
As Earth moves around the Sun, it is continually encountering dust and debris that dates back to the birth of the Solar system. The system is littered with such debris, and the meteors and fireballs seen every night are evidence of just how polluted our local neighbourhood is.

But most of the debris is far too small to cause problems to life on Earth. There is far more tiny debris out there than larger chunks – so impacts from objects that could imperil life on Earth’s surface are much less frequent.

The most famous impact came some 66 million years ago. A giant rock from space, at least 10 kilometres in diameter, crashed into Earth – causing a mass extinction that wiped out something like 75% of all species on Earth.

Impacts that large are, fortunately, very rare events. Current estimates suggest that objects like the one which killed the dinosaurs only hit Earth every 50 million years or so. Smaller impacts, though, are more common.

Asteroid 2024 YR4
The 1-in-77 chance of collision to watch 2024 YR4 has been under close observation by astronomers for a little over a month. It was discovered just a few days after making a relatively close approach to our planet, and it is now receding into the dark depths of the Solar system. By April, it will be lost to even the world’s largest telescopes.

The observations carried out over the past month have allowed astronomers to extrapolate the asteroid’s motion forward over time, working out its orbit around the Sun. As a result, it has become clear that, on 22 December 2032, it will pass very close to our planet – and may even collide with us.

At present, our best models of the asteroid’s motion have an uncertainty of around 100,000 kilometres in its position at the time it would be closest to the Earth. At around 12,000 kilometres in diameter, our planet falls inside that region of uncertainty.

Calculations suggest there is currently around a 1-in-77 chance that the asteroid will crash into our planet at that time. Of course, that means there is still a 76-in-77 chance it will miss us.

How big would the impact be?
At the moment, we don’t know the exact size of 2024 YR4. Even through Earth’s largest telescopes, it is just a single tiny speck in the sky. So we have to estimate its size based on its brightness. Depending on how reflective the asteroid is, current estimates place it as being somewhere between 40 and 100 metres across.

What does that mean for a potential impact?
Well, it would depend on exactly what the asteroid is made of. The most likely scenario is that the asteroid is a rocky pile of rubble. If that turns out to be the case, then the impact would be very similar to the Tunguska event in 1908.