ASTEROIDS • PLANETARY DEFENSE • 2029
Apophis 2029: Earth Is Safe, but the Asteroid May Change
On April 13, 2029, a large asteroid will sweep remarkably close to Earth. The real scientific story is what Earth's gravity may do to Apophis.
MKP EXPLAINER • OCTOBER 18, 2026
What is happening?
Near-Earth asteroid 99942 Apophis, approximately 340 meters across, will pass roughly 32,000 kilometers above Earth's surface on April 13, 2029—inside the altitude of geostationary satellites. NASA has ruled out an Earth impact for at least the next century. A close pass is not the same as a collision.
Why scientists are excited
Earth's gravity will substantially change Apophis's orbit around the Sun. Tidal forces could also alter its spin state, trigger small surface movements, or expose fresh material. These surface effects are research questions, not confirmed future events. Researchers can compare observations before, during and after the flyby to test their models.
What spacecraft will investigate?
NASA's OSIRIS-APEX mission, repurposing the OSIRIS-REx spacecraft after its Bennu sample return, is planned to study Apophis after the encounter. Spacecraft and ground-based observations can reveal the asteroid's shape, rotation, composition and possible changes caused by Earth's gravity.
What the headline gets right—and wrong
It's fair to say that the asteroid, rather than Earth, is the object likely to experience significant physical effects. But “should worry” is figurative: Apophis is not alive, and the exact magnitude of any surface disturbance is uncertain. The scientific opportunity is more important than the dramatic headline.
Questions worth following
- Will the asteroid's rotation measurably change?
- Will tidal stresses shift loose surface material?
- What can the encounter teach us about future asteroid-deflection planning?