When the ‘God of Chaos’ asteroid flies by our planet in five years, Earth’s gravity could cause it to experience ‘astroquakes,’ scientists have predicted.
Their research suggests that when the asteroid Apophis – named for the Egyptian God of Chaos – passes within just 19,000 miles of Earth, our planet’s gravitational pull will cause it to violently shake.
The theoretical shaking could happen due to gravitational tidal forces, which are the stretching or pulling effect on an object caused by the uneven gravitational pull from another massive body.
The team identified two physical processes that could occur. One would cause rocks and dust to fly off the surface, and the other would trigger landslides that would happen gradually over tens of thousands of years.
Both would ultimately change the surface structure of the four-billion-year-old asteroid.
Apophis, set for the flyby on April 13, 2029, is a ‘city-killer’ space rock the size of the Empire State Building.
If it were to hit Earth directly, its impact would be equivalent to detonating tens or hundreds of nuclear bombs, according to The Planetary Society.
It wouldn’t destroy the entire Earth, but it could easily annihilate a city, spreading destruction over a radius of hundreds of miles.
This illustration shows Apophis’ size relative to New York City. A direct hit from this asteroid wouldn’t destroy the whole Earth, but it could wipe out a major metropolitan area
Scientists have paid close attention to this asteroid’s path since it was first discovered in 2004. Initially, the chances of a potential impact in 2029 were relatively high at 2.7 percent.
But more recent studies have found that the odds are closer to one in two billion.
A team of researchers led by Ronald-Louis Ballouz, an asteroid scientist at the Johns Hopkins University Applied Physics Laboratory, investigated what might happen to Apophis when it passes through Earth’s gravitational field.
Asteroids typically have weathered surfaces because they are constantly bombarded by meteoroids in a process called space weathering, Ballouz told Live Science, but astronomers have long observed space rocks that pass close to planets lack weathered surfaces.
He suspected that the reason why could be because the planet’s gravity removes the outer layer of the asteroid’s surface.
To test this, the researchers created a computational models of Apophis and then simulated each model’s path to Earth while tracking its physical changes, revealing our planet’s gravitational pull could drive two different physical processes on Apophis.
The first is earthquake-like tremors that would likely begin about an hour before the asteroid reaches its closest distance from Earth and continue for some time after.
When Apophis encounters Earth’s gravity, it could experience tremors strong enough to lift boulders from its surface and allow some rocks to escape into space, researchers say
It’s difficult to say how intense this shaking will be. But Ballouz expects it will be strong enough to change Apophis’ outer appearance, lifting boulders from the surface and allowing some rocks to escape into space.
The other process is a change in the asteroid’s tumbling. Space rocks like Apophis don’t rotate on an axis, as planets do. Rather, they tumble somewhat haphazardly through space.
Earth’s gravitational pull could alter Apophis’ tumbling pattern, triggering landslides over the course of tens of thousands of years that could further ‘refresh’ its surface to reveal the layers beneath.
The research team’s findings are currently available on the arXiv preprint database, and have been accepted for publication in the Planetary Science Journal.
If Ballouz’s hypothesis proves correct, it could explain why other asteroids that have been subjected to planetary gravity don’t show signs of space weathering on their surfaces.
But he and his team won’t know for sure until NASA’s OSIRIS-APEX mission rendezvous with Apophis during its 2029 flyby.
This spacecraft will study the asteroid for 18 months to document any physical changes that it endured during its encounter with Earth.
As for whether Apophis could directly hit Earth anytime soon, research has determined that we’re safe for at least the next 100 years, according to the Planetary Society.
But to prepare for the unlikely event that another ‘city-killer’ asteroid could collide with Earth, NASA’s Planetary Defense Coordination Office is developing ways to deflect or destroy them before they make impact.
