WASHINGTON (AFP) – A colossal explosion in the sky, unleashing energy hundreds of times greater than the Hiroshima bomb. A blinding flash nearly as bright as the Sun. Shockwaves powerful enough to flatten everything for miles.
It may sound apocalyptic, but a newly detected asteroid nearly the size of a football field now has a greater than one percent chance of colliding with Earth in about eight years.
Such an impact has the potential for city-level devastation, depending on where it strikes.
Scientists aren’t panicking yet, but they are watching closely.
“At this point, it’s ‘Let’s pay a lot of attention, let’s get as many assets as we can observing it,'” Bruce Betts, chief scientist of The Planetary Society, told AFP.
By contrast, 2024 YR4 falls into the “city killer” category.
“If you put it over Paris or London or New York, you basically wipe out the whole city and some of the environs,” said Betts.
The best modern comparison is the 1908 Tunguska Event, when an asteroid or comet fragment measuring 30-50 meters exploded over Siberia, flattening 80 million trees across 770 square miles (2,000 square kilometers).
Like that impactor, 2024 YR4 would be expected to blow up in the sky, rather than leaving a crater on the ground.
“We can calculate the energy… using the mass and the speed,” said Andrew Rivkin, a planetary astronomer at Johns Hopkins Applied Physics Laboratory.
For 2024 YR4, the explosion from an airburst would equal around eight megatons of TNT — more than 500 times the power of the Hiroshima bomb.
If it explodes over the ocean, the impact would be less concerning, unless it happens near a coastline triggering a tsunami.
The good news, experts stress, is that we have plenty of time to prepare.
Rivkin led the investigation for NASA’s 2022 DART mission, which successfully nudged an asteroid off its course using a spacecraft — a strategy known as a “kinetic impactor.”
The target asteroid posed no threat to Earth, making it an ideal test subject.
“I don’t see why it wouldn’t work” again, he said. The bigger question is whether major nations would fund such a mission if their own territory wasn’t under threat.
Other, more experimental ideas exist.
Lasers could vaporise part of the asteroid to create a thrust effect, pushing it off course. A “gravity tractor,” a large spacecraft that slowly tugs the asteroid away using its own gravitational pull, has also been theorised.
If all else fails, the long warning time means authorities could evacuate the impact zone.
“Nobody should be scared about this,” said Fast. “We can find these things, make these predictions and have the ability to plan.”
