‘God of Chaos’ Asteroid Predicted to Crash and Drop Rocks During Flyby of Earth

In a close encounter that could reshape its very structure, asteroid Apophis is expected to experience dramatic surface changes when it passes near Earth on April 13, 2029.

According to new research, this brief interaction with our planet’s gravity could trigger tremors and landslides on Apophis, potentially transforming its surface.

Ronald-Louis Ballouz, an asteroid scientist at Johns Hopkins University’s Applied Physics Laboratory, explains that asteroids like Apophis endure constant “weathering” from bombardment by tiny meteoroids, which gradually alter their surfaces.

However, asteroids that pass close to planets often show less weathering than those further out in space, leading to the theory that planetary gravity could be responsible for refreshing the surfaces of such space rocks.

About Apophis

Apophis, a 1,100-foot-long (340-meter) asteroid named after the Egyptian god of chaos, was discovered in 2004. The peanut-shaped asteroid quickly attracted attention due to its size and its initial close pass by Earth.

Early estimates suggested a higher chance of impact, but by 2021, astronomers had refined their calculations and determined that Apophis, although on a close path, would not collide with Earth. Instead, the asteroid is expected to pass within 20,000 miles (32,000 kilometers) of Earth, which is closer than many of our orbiting satellites.

While this distance is considered safe for Earth, scientists are curious about how this close pass might impact Apophis.

To explore this idea, Ballouz and an international team of researchers developed computational models of Apophis using data from another bilobed asteroid, Itokawa, which has been studied extensively. Their simulations tested how Apophis might respond to Earth’s gravitational pull, simulating both large-scale and small-scale structural effects during the 2029 approach.

Earth’s Gravity and Apophis

Their findings suggest that two main processes—both driven by Earth’s gravity—could significantly alter Apophis’ surface. The first involves seismic tremors, which are expected to begin about an hour before Apophis makes closest approach and continue for a short time after.

Although the intensity of these tremors remains uncertain, Ballouz explained that even minor seismic events on Earth are likely to have a pronounced effect on Apophis because gravity it is about 250,000 times fainter than Earth’s. The tremor could push boulders and rocks loose, causing some to be lifted briefly into space before falling back, creating visible patterns that could be observed by passing spacecraft.

The second transformation process could affect the asteroid’s rotational dynamics, or “turbulence.” Unlike a stable, single-axis rotation, Apophis rotates erratically, similar to a loosely thrown soccer ball.

A separate study published in 2023 found that Earth’s gravity will alter Apophis’ rollover speed, either speeding it up or slowing it down, depending on its orientation as it approaches Earth.

The new simulations support this and further reveal that such changes could destabilize the rock slopes on its surface. Over time, this gradual destabilization could even trigger landslides.

Future plans

To better understand these changes, Ballouz and his team hope to collect real-time data from NASA’s OSIRIS-APEX mission. This spacecraft, reused from the OSIRIS-REx mission that collected samples from asteroid Bennuis due to observe Apophis during its 2029 transit.

For 18 months, OSIRIS-APEX will study ApophisIts chemical composition also documents surface changes, potentially validating Ballouz’s hypotheses and providing new insights into the effects of planetary encounters on small bodies.

As Apophis approaches, the scientific community is braced for a rare observational opportunity. This close encounter could illuminate not only the processes that shape asteroids, but also the complex dynamics of space weathering and planetary interactions.

The study is currently available on arXiv preprint database.