The YR4 asteroid, which has been dubbed the “city killer”, now has a 3.1% chance of hitting the Earth in 2032, making it the most threatening space body recorded in modern times.

The asteroid was first discovered by the El Sauce Observatory in Chile at the end of December and is estimated to be 40 to 90 metres in diameter. While asteroids of that size do not pose a threat to humanity overall, it would be large enough to flatten a city and cause major damage and disruption in a localised area.

Its discovery triggered the first step in planetary defence responses, prompting several major telescopes to gather data about the object and leading United Nations-endorsed space agencies to begin planning asteroid threat mitigation.

It made a close approach of the Earth at the end of December two days prior to its discovery – around 828,800km from the atmosphere, or just over twice the distance of the Earth to the Moon. It is now moving away from the planet and its next close approach will not be...