A huge asteroid that was briefly feared to strike Earth now has a nearly four percent chance of smashing into the Moon, according to new data from the James Webb Space Telescope.

The asteroid, thought to be capable of leveling a city, set a new record in February for having the highest chance — 3.1 percent — of hitting our home planet than scientists have ever measured.

Earth’s planetary defence community leapt into action and further observations quickly ruled out that the asteroid — called 2024 YR4 — will strike Earth on 22 December 2032.

But the odds that it will instead crash into Earth’s satellite have been steadily rising.

After the Webb telescope turned its powerful gaze towards the asteroid last month, the chance of a Moon shot is now at 3.8 percent, NASA said.

“There is still a 96.2 percent chance that the asteroid will miss the Moon,” NASA said in a statement on Thursday.

Richard Moissl, head of the European Space Agency’s planetary defense office, told AFP that this aligned with their internal estimates of around four percent.

The new Webb data also shed light on the size of the space rock, which was previously estimated to be between 40 and 90 meters (131 to 295 feet).

It is now believed to be 53 to 67 meters, roughly the height of a 15-story building.

This is significant because it is bigger than the 50-meter threshold for activating planetary defense plans.

If the asteroid still had a more than one percent chance of hitting Earth, “the development of one or more deflection missions would already be starting now,” Moissl said.

There are a range of ideas for how Earth could fend off an oncoming asteroid, including nuclear weapons and lasers.

But only one has been tested on an actual asteroid. In 2022, NASA’s DART mission successfully altered a harmless asteroid’s trajectory by smashing a spacecraft into it.

‘Perfect opportunity’

While no one wanted to need to test Earth’s defenses on the potentially hugely destructive asteroid 2024 YR4, many scientists are hoping it will strike the Moon.