Apophis will be visible to the naked eye as a slowly moving star-like point of light, roughly as bright as stars you can comfortably spot from a suburban backyard. On the evening of April 13, 2029, the asteroid will pass closer to Earth than some of our highest-orbiting satellites, reaching a peak brightness around magnitude 3.1. That makes it comparable to the fainter stars in well-known constellations, bright enough to see without binoculars but not a dazzling spectacle. What makes it extraordinary isn’t its brilliance but its motion: a point of light drifting visibly across the sky, something no one alive has ever witnessed from an asteroid this large.
How Bright It Will Be and Who Will See It
At its closest, Apophis will shine at roughly third magnitude. For reference, most of the stars that form the Big Dipper are around second magnitude, and most people in moderately light-polluted areas can see stars down to about fourth magnitude without any optical aid. So Apophis will sit comfortably within naked-eye range, though it won’t be among the brightest objects in the sky. You won’t mistake it for a planet like Venus or Jupiter. Through binoculars or a small telescope, it will simply appear as a sharper point of light, since at its size (roughly 370 meters across) and distance it won’t show a visible disk.
The best views at closest approach will belong to observers in Europe, Africa, and western Asia, where the asteroid will be above the horizon during the minutes around perigee. From the eastern United States, Apophis will still be visible earlier in the evening as it approaches, though it will be fainter and higher in altitude. Observers in the western Americas, eastern Asia, and Australia will largely miss the closest moments due to the geometry of when their part of the planet faces the asteroid’s track. Weather permitting, anyone in the favored zones with a clear view of the sky and modest patience will be able to watch it drift among the stars.
A Point of Light That Visibly Moves
What will set Apophis apart from everything else in the sky that night is its speed. At closest approach, it will move at roughly 42 degrees per hour across the star field. That’s fast enough to cover the apparent width of the full Moon in about one second. In practical terms, if you hold your gaze on a patch of sky, you’ll see the point of light glide through it in real time, without needing time-lapse photography or patience. It will look something like a slow satellite pass, except satellites at low orbit move faster and are lit only briefly, while Apophis will be visible for hours as it brightens on approach and fades afterward.
For most of the evening before closest approach, the apparent speed will be much slower, and the asteroid will look more like a gradually brightening star that subtly shifts position over tens of minutes. The dramatic drift happens during the closest hour or so. After perigee, the asteroid will dim as it recedes, fading back below naked-eye visibility within a few hours. Astrophotographers with tracking mounts will likely capture striking images of its streak against background stars, but the visual experience for a casual observer will be that of a moderately bright “star” traveling in a smooth line through familiar constellations.
Closer Than Geostationary Satellites
Part of what makes this event so striking is the sheer proximity. Apophis will pass about 31,860 kilometers from Earth’s surface, well inside the ring of geostationary satellites that orbit at roughly 35,800 kilometers altitude.1U.S. Geological Survey. Countdown to Apophis Close Approach—Cascading Hazards from Asteroid Impacts That distance is roughly a tenth of the way to the Moon. No known asteroid of this size has been observed passing so close in the era of modern astronomy.
The natural question is whether it poses any danger to those satellites. The geometry of the flyby means Apophis will pass through the geostationary belt at a point and angle that does not line up with the dense band where most communications and weather satellites sit.1U.S. Geological Survey. Countdown to Apophis Close Approach—Cascading Hazards from Asteroid Impacts Researchers have also modeled the interaction more specifically. A study in The Planetary Science Journal examined the potential for Apophis to interact with the high Earth orbit satellite population and confirmed the flyby will occur closer than geostationary orbit, but the risk to individual satellites is negligible because of how thinly spread they are across that vast shell of space.2The Planetary Science Journal. Potential Interaction of 99942 Apophis with the High Earth Orbit Population during the 2029 Close Approach
How Rare Is a Flyby Like This?
Close asteroid passes happen regularly in the sense that small, car-sized rocks zip past Earth inside the Moon’s orbit multiple times a year. What makes Apophis different is its size combined with its proximity. An asteroid roughly 370 meters wide coming within 38,000 kilometers of Earth is a genuinely rare event. A study published in Astronomy & Astrophysics estimated that for the broader population of Apophis-like near-Earth objects, an encounter this close happens roughly once every 13,000 years. For Apophis specifically, accounting for its individual orbit, the frequency is even lower: approximately once every 430,000 years.3Astronomy & Astrophysics. Apophis source population and Earth encounter frequency of Apophis-like bodies
That context matters for appreciating the 2029 flyby as a scientific opportunity, not just a public spectacle. Planetary scientists have decades of telescopic observations of asteroids, but nearly all of that data comes from distances of millions of kilometers. Having a sizable asteroid pass close enough to resolve in radar, close enough to send a spacecraft alongside with just months of travel, and close enough that Earth’s gravity measurably alters the asteroid itself is an opportunity that no one planned and that may not repeat in recorded human history.
What Earth’s Gravity Will Do to Apophis
Apophis isn’t just passing by for our viewing pleasure. The flyby is close enough that Earth’s tidal forces will physically alter the asteroid. Researchers have modeled these effects in detail, and the expected changes go beyond a simple gravitational tug on its orbit.
A study in the Monthly Notices of the Royal Astronomical Society focused on what the tidal encounter at a perigee distance of about 5.96 Earth radii will do to the asteroid’s surface and structure. The findings predict that the flyby will change both Apophis’s orbit and its rotation. Earth’s tidal torques are expected to shift the asteroid’s spin state, and the gravitational stresses could trigger surface refreshing, meaning that buried material gets exposed and weathered surface grains shift or fall away.4Monthly Notices of the Royal Astronomical Society. Tidal resurfacing model for (99942) Apophis during the 2029 close approach with Earth The researchers also noted the possibility of small-scale structural modifications, seismic vibrations through the body, and stress changes around a known concave region on Apophis’s surface.
The surface refreshing aspect is particularly interesting because it may be directly detectable. Asteroids that spend long periods in space develop a weathered veneer from solar radiation and micrometeorite impacts. If Earth’s gravity shakes loose enough of that layer to expose fresher material underneath, telescopes and spacecraft instruments could spot a change in the asteroid’s color and reflectivity between before and after the encounter. In effect, the flyby serves as a natural experiment that would take human engineers enormous effort to replicate.
Spacecraft Racing to Meet It
Two space agencies have missions planned to observe Apophis during and after the 2029 encounter. The more advanced of the two is OSIRIS-APEX, a repurposed extension of NASA’s OSIRIS-REx mission, the spacecraft that successfully collected a sample from asteroid Bennu and returned it to Earth in September 2023. After releasing its sample return capsule, the spacecraft was redirected into an orbit that will bring it to Apophis in 2029.5The Planetary Science Journal. OSIRIS-APEX: An OSIRIS-REx Extended Mission to Asteroid Apophis
OSIRIS-APEX will observe the asteroid from a distance during the Earth flyby itself, capturing the tidal disturbance as it unfolds. Then, beginning in July 2029, the spacecraft will move in closer to begin high-resolution mapping and characterization of the surface. Apophis is classified as a “stony” (S-type) asteroid, a different composition class from the carbon-rich Bennu, so the data will fill a gap in our understanding of how these more common asteroid types are structured. Near the end of the mission, OSIRIS-APEX plans to use its thrusters to blast the surface and excavate regolith, a technique the spacecraft demonstrated at Bennu. Observing what gets kicked up and what lies underneath will reveal information about the subsurface material properties that surface imaging alone cannot provide.5The Planetary Science Journal. OSIRIS-APEX: An OSIRIS-REx Extended Mission to Asteroid Apophis
The European Space Agency has also planned a mission called RAMSES (Rapid Apophis Mission for Space Safety), intended to rendezvous with Apophis before or during its Earth encounter. RAMSES would provide an independent set of observations from a European instrument suite, giving scientists complementary data and, critically, a before-and-after comparison of the asteroid’s physical state around the flyby. The mission’s timeline is tight given the fixed date of the encounter, and its status depends on funding and launch readiness decisions still being finalized.
The Force That Makes Apophis Hard to Track
Predicting exactly where Apophis will be decades into the future is harder than for most asteroids, and the reason has nothing to do with gravitational uncertainty. The main complication is the Yarkovsky effect, a subtle force created by the way an asteroid absorbs sunlight on one side and re-emits that energy as heat, producing a tiny but persistent push. For a body as small as Apophis, this thermal thrust is the leading source of uncertainty in long-term orbit predictions.6Communications Earth & Environment. Non-zero Yarkovsky acceleration for near-Earth asteroid (99942) Apophis
The 2029 flyby itself will make this even more complicated going forward. Because Earth’s gravity will alter Apophis’s spin rate and the orientation of its rotation axis, the strength and direction of the Yarkovsky effect will change after the encounter. Researchers at Pulkovo Observatory modeled this and found that the post-flyby Yarkovsky drift could vary by more than a factor of ten, with the average rate of change in the asteroid’s orbital size ranging from about negative 235 to negative 20 meters per year depending on the new rotational state.7Publications of the Pulkovo Observatory. About the Yarkovsky effect in the dynamics of asteroid (99942) Apophis That spread matters because it affects how precisely scientists can predict Apophis’s position during later close approaches in 2036 and beyond. The 2029 flyby will provide the measurements needed to pin down the new spin state, which in turn will tighten those future predictions dramatically.
Why It Won’t Hit Earth
Apophis has a colorful history with public fear. When it was discovered in 2004, initial orbit calculations suggested a concerning chance of an Earth impact in 2029, with early estimates running as high as roughly 1 in 37. That was enough to briefly give Apophis the highest hazard rating ever assigned to an asteroid on the Torino Scale. As additional observations refined the orbit, the 2029 impact was ruled out entirely, and subsequent close approaches in 2036 and 2068 were also cleared. The asteroid’s trajectory is now known precisely enough that it poses no impact risk for at least a century.6Communications Earth & Environment. Non-zero Yarkovsky acceleration for near-Earth asteroid (99942) Apophis
Part of the concern in the early years centered on so-called gravitational keyholes, narrow corridors in space through which the asteroid’s 2029 path could have been deflected into a collision course during a later orbit. Refined observations, including precise measurements of the Yarkovsky effect, confirmed that Apophis will not pass through any of the keyholes that would set up a future impact. The episode is often cited as a case study in how planetary defense works: initial uncertainty can produce scary-sounding numbers, but the system of follow-up observations and orbit refinement is designed to resolve those ambiguities, and in Apophis’s case, it did exactly that.
If Apophis Did Hit, What Would Happen?
Even though impact has been ruled out, the question lingers for good reason: Apophis is a useful benchmark for thinking about asteroid threats. At roughly 370 meters across, it sits in the size range where an impact would be a regional catastrophe but not a civilization-ending event. Researchers have modeled what a hypothetical deep-ocean impact would produce, analyzing crater formation, the resulting earthquake, atmospheric overpressure, ejected material, thermal radiation, and tsunami generation.8Acta Astronautica. Hypothetical Apophis deep ocean impact—Energy analysis The modeling included best-case, expected, and worst-case scenarios to bracket the range of possible outcomes.
An ocean impact would be the more common scenario simply because oceans cover most of Earth’s surface. The primary concern would be tsunami waves radiating outward from the impact point, with the severity depending on the depth of the water, the angle of entry, and the distance to populated coastlines. A land impact would produce a crater roughly a few kilometers across and devastate an area comparable to a small country, but the effects would be more localized than the global consequences of the much larger asteroid that ended the dinosaurs. The energy involved is measured in hundreds of megatons of TNT equivalent, enormous by human standards but modest on the scale of asteroid impacts the Earth has experienced over geologic time.
What Binoculars and Telescopes Will Reveal
For amateur astronomers, Apophis’s 2029 flyby will be an unusual observing target. Through binoculars, the asteroid will appear as a bright, steadily moving point, easily distinguishable from stars by its motion. A small telescope at moderate magnification won’t show surface detail (the asteroid’s apparent size will still be far too small to resolve as a disk), but it will make the object easier to track and brighter against the background. Observers with motorized tracking mounts will be able to keep the asteroid centered and watch background stars streak past, creating a dramatic visual and photographic effect.
The real scientific value of ground-based observations lies in radar and spectroscopy rather than optical imaging. Goldstone and Arecibo-class radar facilities (with Goldstone being the primary asset since Arecibo’s collapse in 2020) will be able to map Apophis’s shape and surface features in detail during the close approach. Spectroscopic observations from professional observatories will track whether the asteroid’s surface composition appears to change as a result of the tidal stresses described earlier, looking for the spectral signature of freshly exposed material versus space-weathered regolith. Those observations, combined with data from OSIRIS-APEX, will give scientists an unprecedented before-and-after comparison of an asteroid disturbed by planetary tidal forces.
For anyone planning to observe, the key logistical detail is that the closest approach happens on a Friday evening (April 13, 2029), which is convenient for public observing events. Astronomy clubs, observatories, and science centers across Europe and Africa are already discussing plans for public viewing nights. The event is accessible enough that even casual skywatchers who have never used a telescope should be able to see it, weather cooperating, simply by looking up at the right part of the sky at the right time and watching for the “star” that moves.