On April 13, 2029, the asteroid 99942 Apophis, nicknamed the 'God of Chaos,' will pass by Earth at a distance of approximately 19,000 miles (30,600 km). This 'ultra close' flyby, well within the orbit of some geosynchronous satellites, is expected to make the asteroid visible to 90% of the world's population with the naked eye, according to new maps revealed at the Apophis T–3 Years workshop in Padua, Italy.
Apophis, a space rock measuring about 450 meters (1,500 feet) wide, will appear as a bright star slowly traversing the night sky for several hours. Unlike meteors that glow from atmospheric entry, Apophis will be visible by reflecting sunlight. The timing of its closest approach, around 21:45 GMT, will allow roughly 1.9 billion people in eastern South America, northern Africa, and parts of Europe to observe it. The flyby begins around 15:00 GMT, offering initial viewing opportunities for about 4.5 billion people in Australia and Asia. The asteroid is predicted to reach its peak brightness at 20:35 GMT.
For viewers in the United Kingdom, Apophis will become visible around 20:00 GMT as twilight begins, remaining in view until it fades. Scientists describe the event as a 'special opportunity to clearly see an asteroid perceptively move against the starry background,' and a 'science bonanza' for studying asteroids.
Apophis, named after the Egyptian god of chaos, was discovered in 2004. Initially, there was a one in 37 chance of impact, but subsequent observations have reduced this probability to zero for the next 100 years. Scientists are certain there is no risk of collision during the 2029 flyby.
Astronomers will closely monitor Apophis as it passes through Earth's gravitational influence, as this close encounter could potentially alter its orbit. Research suggests that the gravitational tug might shift Apophis from its current path, potentially increasing the likelihood of a future collision, though still not within the immediate future. This close pass is expected to yield crucial data for planetary defense strategies. NASA's OSIRIS–APEX mission and other spacecraft will observe Apophis, looking for changes in its structure or trajectory. The insights gained from studying Apophis's composition and dynamics are vital for understanding how to deflect future Earth-bound asteroids.
This event builds on efforts like NASA's Double Asteroid Redirection Test (DART), which successfully demonstrated the kinetic impactor technique by altering an asteroid's orbit. Results from that mission are expected to be confirmed by the European Space Agency's Hera mission in December 2026. The study of asteroids like Apophis is crucial for developing effective strategies to protect Earth from potential impacts.