On April 13, 2029, the asteroid Apophis will pass so close to Earth that it will be visible to the naked eye for over two billion people. It will be the first time in recorded history that a potentially hazardous asteroid of this size can be seen without a telescope. This extraordinary event — described by planetary scientists as a “once-in-a-millennium” natural experiment — was presented during the Europlanet Science Congress in Helsinki and reported by Live Science.
Apophis: From Chaotic Beginnings To Cosmic Opportunity
Discovered in 2004, Apophis — officially named 99942 Apophis — sparked early fears after orbital models suggested a 2.7% chance of impact in 2029. That slim but serious possibility placed it at Level 4 on the Torino Scale, making it the highest-rated threat ever recorded among near-Earth objects.
Over the years, continued radar tracking dramatically refined Apophis’ predicted path. By 2021, astronomers were confident enough to remove it from all risk lists, with no impact risk for at least the next century. According to MIT planetary scientist Richard Binzel, the key message remains: “Apophis will safely pass the Earth.”
Even so, a recent study pointed out a vanishingly small chance — less than one in a billion — that an unknown object could nudge Apophis into a different orbit. Scientists say they’ll need about three more years to fully rule out even that extremely unlikely scenario.
Earth’s Gravity Is About To Leave A Mark
This flyby won’t affect Earth in any noticeable way, but Apophis itself is expected to undergo dramatic changes. The asteroid will pass at an altitude of just 18,600 miles (30,000 kilometers) — lower than many of our geostationary satellites — giving researchers an unprecedented chance to witness how Earth’s gravitational pull distorts a celestial body in real time.
Apophis currently follows an Aten-class orbit, which means it spends most of its time inside Earth’s orbital path. After the flyby, that orbit will shift into a wider Apollo-class trajectory. Its rotation may also change, possibly triggering a new tumbling motion, according to Binzel. “The Earth won’t care, but Apophis will care,” he emphasized. “It’s all about the encounter physics.”
The flyby may also allow scientists to detect seismic activity within the asteroid. Binzel explained that in six decades of space exploration, seismicity has only been measured on two worlds: the Moon and Mars. Apophis could become the third.
Missions Are Gearing Up For A Rare Real-time Experiment
NASA is already positioning itself to take full advantage of this event. Its OSIRIS-REx spacecraft — fresh from its successful sample-return mission from the asteroid Bennu — has been reassigned to rendezvous with Apophis. Now renamed OSIRIS-APEX, the probe is expected to reach the asteroid ahead of the flyby and will map its surface, rotation, and structural changes.
European Space Agency is developing its own complementary mission, RAMSES (Rapid Apophis Mission for Space Safety). If funding is approved at the ESA’s Ministerial Council in November, the spacecraft could launch in spring 2028 and arrive at Apophis by February 2029.
According to Monica Lazzarin, a physics professor at the University of Padua, RAMSES will fly as close as 5 kilometers from the asteroid during its flyby. The mission will look for dust plumes, track changes in its orbit, and may deploy a cubesat to land on the surface and monitor internal vibrations.
A Milestone For Planetary Defense Science
Researchers are also framing Apophis as a critical test case for planetary defense strategies. Even though it poses no threat, Apophis is part of a class of potentially hazardous near-Earth asteroids that humanity must eventually learn to manage.
By tracking how Earth’s gravity changes Apophis — in shape, spin, and orbit — scientists can update the impact modeling tools that would guide any future asteroid deflection mission. Tom Statler, a planetary scientist at NASA headquarters, made this clear: “Apophis is not a planetary defense emergency. It is an opportunity, and an unprecedented one.” He also offered a reassuring perspective. “Asteroids are not something to be scared of,” he said. “They’re something to understand — and that’s what we’re doing.”
