A city-killer asteroid will skim below our satellites in 2029

On April 13, 2029, an asteroid roughly 340 meters across will pass within about 32,000 kilometers of Earth’s surface, closer than the ring of geostationary satellites that relay television signals and weather data around the planet. The object, named Apophis after the Egyptian god associated with chaos, will be visible to the naked eye across parts of Europe, Africa and Asia during the pass, marking the closest approach of an asteroid this large that astronomers have ever been able to predict and prepare for in advance.

A 2004 Discovery That Briefly Alarmed Astronomers

Astronomer Roy Tucker first spotted Apophis in June 2004, and early orbital calculations triggered genuine concern, showing a real possibility of impact during close approaches in 2029, 2036 or even 2068. The object was formally named after an Egyptian deity associated with chaos and darkness following a public naming contest, a choice that only added to the ominous headlines the asteroid generated in its early years of tracking. That initial uncertainty made Apophis one of the highest-profile objects ever tracked by planetary defense programs, briefly registering the highest threat rating ever assigned on the Torino impact hazard scale, a 10-point system astronomers use to communicate the relative urgency of an asteroid’s collision risk to the public. Additional observations over the following years steadily narrowed the asteroid’s projected path, and astronomers have since ruled out any impact risk for at least the next century, converting Apophis from a genuine hazard into a rare scientific opportunity.

Closer Than the Satellites That Orbit Above It

Geostationary satellites orbit at roughly 36,000 kilometers above Earth’s surface, which means Apophis will pass beneath that entire ring of infrastructure during its 2029 flyby. At an estimated mass of about 27 million tons, the asteroid is large enough that a pass this close would ordinarily be treated as a near miss requiring monitoring, except that its orbit is now known precisely enough to rule out any collision. The close distance is also why the flyby will be visible without a telescope, appearing briefly as a fast-moving point of light before continuing on its path around the sun.

Why It Counts as a City-Killer, Not an Extinction Event

Asteroids in Apophis’s size class fall into a category researchers describe informally as city-killers: large enough to destroy a metropolitan area and cause damage across a much wider region if they struck a populated area directly, but far smaller than the roughly 10-kilometer object linked to the extinction of the dinosaurs. That size range is also part of what makes Apophis useful scientifically. It is large enough to study in detail with ground telescopes and spacecraft instruments, yet its close 2029 pass means researchers can observe it without waiting decades for another opportunity.

Spacecraft Racing to Meet It

Two space agencies are sending hardware to take advantage of the flyby. NASA redirected its OSIRIS-REx spacecraft, renamed OSIRIS-APEX after completing its earlier mission to asteroid Bennu, to rendezvous with Apophis shortly after the 2029 close approach and study how Earth’s gravity affects the asteroid’s surface and rotation during the pass. The European Space Agency is separately preparing to send its own spacecraft, under a mission concept named Ramses, to reach Apophis around the same period, aiming to observe the asteroid before, during and after the encounter rather than only afterward. Ground-based telescopes and radar facilities around the world are also expected to track the approach in real time, and amateur observers in the flyby’s visibility zone are expected to be able to watch it cross the sky without specialized equipment.

What the Flyby Will Teach About Planetary Defense

Earth’s gravity itself is expected to visibly affect Apophis during the pass, potentially altering its rotation rate and even triggering minor surface disturbances such as landslides on the asteroid, effects researchers rarely get to observe directly. Studying those changes in real time offers a natural experiment that would otherwise require sending a spacecraft to deliberately disturb an asteroid, informing future planetary defense techniques such as kinetic impactor deflection missions. The data will also refine models used to predict how other near-Earth objects might behave during their own close approaches.

No Repeat Risk Expected Soon

Once Apophis completes its 2029 pass, current models show it will not approach Earth this closely again for many decades, and the earlier fears tied to 2036 and 2068 impact scenarios have been fully retired based on refined tracking. Continued observation after 2029 will still matter, since even small unmodeled forces, similar to the effects studied on asteroid Bennu, can shift long-term orbital predictions. For now, astronomers consider Apophis a solved risk and an open scientific opportunity, arriving at a distance close enough to see, but not close enough to fear. Mission teams on both the NASA and European projects have said the 2029 window is unlikely to repeat itself for a similarly sized object within the careers of scientists currently working on it, adding urgency to the preparations already underway.

This article was produced with the assistance of AI and reviewed by an editor.

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