Researchers have mapped the 2029 flyby of asteroid Apophis, predicting that up to 90% of Earth's population could see the object with the naked eye as it passes closer than many satellites, offering a rare opportunity for direct observation
In April 2029, the asteroid 99942 Apophis is projected to pass unusually close to Earth, offering a rare opportunity for direct observation by billions of people. New visibility maps presented at the Apophis T-3 Years workshop in Padua, Italy, indicate that as many as 7.6 billion people—approximately 90% of the global population—could witness the flyby with the unaided eye, provided local conditions are favorable. This event marks the first time astronomers have been able to predict a naked-eye asteroid flyby of this scale in advance.
How Close Apophis Will Come to Earth
Apophis is a near-Earth asteroid with an elongated, peanut-like shape, measuring about 450 meters across at its widest point. Its size is sufficient to cause regional devastation in the event of an impact, but current orbital calculations show no risk of collision with Earth during the 2029 encounter or for at least the next century. The asteroid's orbit, which now lies between those of Venus and Earth, brings it around the Sun every 10.5 months. The name Apophis derives from the Egyptian deity Apep, associated with chaos and darkness, reflecting the asteroid's potential hazard classification.
On 13 April 2029, Apophis will approach Earth to within roughly 30,600 kilometers—closer than many geosynchronous satellites but still well above the International Space Station and low Earth orbit. This proximity will make the asteroid visible as a moving point of light, comparable in brightness to the stars of the Big Dipper, and distinguishable from satellites by its slower apparent motion across the sky. The flyby will last about seven hours, with the asteroid traversing several well-known constellations as seen from different regions of the world.
Where the Asteroid Will Be Visible
Visibility will depend on local night and twilight conditions, as well as clear skies and minimal light pollution. At the start of the flyby, Apophis may be visible to around 4.5 billion people across Australia and much of Asia. As the asteroid draws closer, peak visibility is expected for up to 5.7 billion people in eastern Africa, southern Europe, Australia, and all of Asia and the Middle East.
By the end of the event, approximately 1.9 billion people in eastern South America, northern Africa, and parts of Europe could still observe the asteroid. North America, however, will largely miss the event due to daylight and unfavorable viewing geometry.
A Major Test for Planetary Defense
There is currently no credible scenario in which Apophis will impact Earth during the 2029 flyby, according to orbital models and risk assessments. However, some researchers note that gravitational interactions during the close approach could alter the asteroid's trajectory or physical structure, potentially affecting future risk calculations.
To address these uncertainties, astronomers plan to coordinate global observations using ground-based telescopes and spacecraft flybys, including NASA's OSIRIS-APEX mission, which aims to study Apophis's composition and motion in detail. The United Nations has designated 2029 as the International Year of Asteroid Awareness and Planetary Defence, underscoring the scientific and public interest in this event.
Beyond its scientific value, the Apophis flyby is expected to serve as a catalyst for public engagement with planetary science and asteroid research. The event's accessibility to a vast portion of the world's population is likely to inspire new interest in observational astronomy, much as previous high-profile astronomical events have done. For context, the excitement generated by major discoveries—such as the detection of a hidden giant planet in the Beta Pictoris system using the James Webb Space Telescope, as reported in Science Report's coverage of exoplanet imaging—demonstrates the public's appetite for direct encounters with astronomical phenomena.
For those able to observe Apophis, the asteroid will appear as a modestly bright star moving slowly against the background of familiar constellations. Observatories in the Canary Islands are expected to capture some of the best images, while amateur astronomers across the Eastern Hemisphere will have a unique opportunity to track the asteroid's progress in real time.
How Astronomers Track Close Approaches
The 2029 Apophis flyby represents a rare convergence of orbital mechanics, observational opportunity, and public accessibility. While the event poses no immediate threat, it provides a valuable test case for planetary defense strategies and a reminder of the dynamic nature of near-Earth space.
Understanding how astronomers predict and monitor asteroid flybys relies on precise orbital calculations and continuous tracking. Observatories use radar, optical telescopes, and spacecraft data to refine an asteroid's trajectory, accounting for gravitational influences from planets and the Sun. These calculations are updated as new observations become available, reducing uncertainty in the predicted path.
For close approaches like Apophis in 2029, even small changes in velocity or position can have significant effects on future orbits, making ongoing monitoring essential for accurate risk assessment and planetary defense planning.
