The ‘God of Chaos’ asteroid can undergo dramatic changes during its flyby of Earth

Scientists predict that asteroid Apophis may undergo significant surface changes when it approaches Earth in 2029, according to a new study.

The asteroid, named after Egyptian god of chaoswill pass within 20,000 miles of Earth on April 13, 2029 — closer than some man-made satellites.

While this proximity presents no danger to Earthresearchers believe the encounter could literally shake the 1,100-foot-long space rock.

Asteroids that pass near planets frequently show unexpectedly fresh surfaces, a phenomenon that has puzzled scientists for some time.

Using computational models based on similar asteroids, Ronald-Louis Ballouz, principal investigator at Johns Hopkins University’s Applied Physics Laboratory, and his team identified two key processes that could reshape Apophis.

First, Earth’s gravitational pull is expected to trigger tremors across the asteroid, starting about an hour before closest approach. While these quakes may seem mild by Earth standards, they could be powerful enough in Apophis’ extremely low gravity to dislodge surface rocks and create distinctive patterns.

The second process involves changes in the erratic overturning motion of the asteroid. Like a poorly thrown football, Apophis does not rotate on a fixed axis. Earth’s gravitational influence could alter this overturning pattern, potentially triggering landslides over thousands of years as surface materials gradually destabilize.

“Apophis’ gravity is about 250,000 times less than Earth’s,” Ballouz told Live Science. “So we think much smaller-scale events could plausibly shake things up on its surface.”

NASA’s OSIRIS-APEX mission, repurposed from the successful OSIRIS-REx asteroid sample return mission, will have a front-row seat to observe these potential changes.

The spacecraft is scheduled to spend 18 months studying Apophis during and after its encounter with Earth, providing unprecedented insights into how planetary flybys can reshape such ancient space rocks.

This research could help resolve long-standing questions about how close encounters with planets can alter the surfaces of asteroids, potentially advancing our understanding of solar system dynamics and asteroid evolution.

“(The results) introduce a new mechanism for the surface refreshment of asteroids, which may provide an answer to a decades-long question about how planetary encounters can alter small body surfaces,” Ballouz said.

The study is currently available on arXiv preprint database, with official publication forthcoming in Journal of Planetary Sciences.

While previous observations have confirmed that Apophis will pose no threat of impact on Earth during its flyby, the encounter promises to give scientists a unique opportunity to witness the asteroid’s evolution in action.

Why is the asteroid called the “God of Chaos”?

Apophis is the ancient Greek name for the Egyptian god of chaos Apep. The deity it is also associated with earthquakes, thunder, darkness, storms and death, and was widely regarded as the most powerful force of evil in Egyptian theology.

In ancient Egyptian art, Apophis was often depicted as a massive serpent, embodying chaos and darkness.

As the main enemy of the sun god Ra, he engaged in nightly battles against Ra’s journey through the underworld. Although Apophis was defeated each night, he could never be completely destroyed, symbolizing the perpetual battle between order and chaos.

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Reference

Ballouz, R.-L., Agrusa, H., Barnouin, OS, Walsh, KJ, Zhang, Y., Binzel, RP, Bray, VJ, DellaGiustina, DN, Jawin, ER, DeMartini, JV, Marusiak, A. , Michel, P., Murdoch, N., Richardson, D.C., Rivera-Valentín, E.G., Rivkin, A.S., and Tang, Y. (2024). Shaking and overturning: short- and long-scale mechanisms for resurfacing near-Earth asteroids from planetary tides and predictions for the 2029 encounter with Earth by (99942) Apophis (No. arXiv:2406.04864). arXiv.