An asteroid up to 100 metres wide has a 1-in-83 chance of impacting Earth on 22 December 2032. That risk of impact is enough to have triggered global planetary defence response procedures for the first time.
鈥淭his is a historic moment,鈥� says at the European Space Agency (ESA).
The asteroid, dubbed 2024 YR4, was first detected on 27 December 2024 by an automated telescope in Chile that scans for asteroids. It is now at the top of ESA and NASA鈥檚 impact , with a 1.3 per cent chance of colliding with Earth in about seven years.
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That risk of collision combined with the asteroid鈥檚 size gives it a rating of 3 out of 10 on the 鈥� a tool used to categorise the potential damage from the impact of comets and asteroids. That means it qualifies as a 鈥渃lose encounter鈥� that could cause 鈥渓ocalized destruction鈥�. The kinetic energy released on impact could be equivalent to nearly 8 million tonnes of dynamite, according to NASA figures, enough to destroy a city.
鈥淭his particular score has never been assigned to any asteroid,鈥� says Moissl. 鈥淭orino scale 3 gives us a mandate to do things we don鈥檛 normally do,鈥� he says, such as ramping up close monitoring.
Collecting measurements of the asteroid from more powerful telescopes could give a more accurate idea of its collision risk with Earth. This may shift the risk to zero, says Moissl.
The asteroid which will pass near Earth in 2029, was initially assigned a 4 on the Torino scale when it was first detected in 2004. After more measurements, the risk was downgraded to zero. That detection occurred before globally coordinated planetary defence procedures, as well as automated asteroid detection systems, were in place.
But 2024 YR4 is getting a different treatment. Moissl says a United Nations-affiliated group called the International Asteroid Warning Network is now working to study the asteroid鈥檚 trajectory. Another international consortium called the Space Mission Planning Advisory Group has also been alerted about the asteroid and could begin planning a proposal on how to defend against a collision, such as deflecting the asteroid with a spacecraft or other means, should that ever become necessary.
Currently, the asteroid 鈥渋s not cause for concern鈥�, says Moissl. 鈥淏ut because it is so unusual, it is something to keep a close eye on.鈥�
