Apophis — inside the satellite belt
A 370-m asteroid passes 32,000 km up — inside the geostationary ring, visible to the naked eye. Nothing this large has come this close in recorded history.
The moment of Apophis — inside the satellite belt: https://nowsky.org/e/apophis-flyby — opens at the right place and time, replayable, no login.
Available views: Orbit ✓ · Sky — (not visible in the sky)
The story
On Friday, 13 April 2029, an asteroid roughly 370 metres across passes about 32,000 km above Earth's surface — inside the ring where geostationary satellites orbit. Nothing this large has come this close in recorded history, and statistically an encounter like it is a once-in-a-few-thousand-years event.
For a while after its discovery in 2004, Apophis was the most famous asteroid on Earth. Early orbit solutions briefly put the chance of a 2029 impact as high as 2.7%, the highest Torino Scale rating ever assigned. More observations erased that possibility, and once radar had tightened the orbit, analysts ruled out any impact for the next century — including the 2068 return that had stayed on the watch list longest.
What is left is not a hazard but a spectacle. Around closest approach, observers across Europe and Africa will see Apophis as a star of third or fourth magnitude. An asteroid visible to the unaided eye is remarkable enough; this one will also be visibly moving, shifting against the background constellations fast enough to follow in real time. No human has watched that happen before.
The name comes from the Egyptian serpent of chaos that tried to swallow the Sun's barque — a fossil of the alarm the discovery caused. The 2029 pass turns that alarm into a celebration. NASA's OSIRIS-APEX is due to join the asteroid shortly after the flyby, and ESA has been preparing a spacecraft intended to arrive before it.
Why it matters
The scientific value of the encounter is that Earth itself becomes the apparatus. Small bodies like Apophis are generally thought to be rubble piles — loose aggregates held together by weak gravity rather than solid rock. What happens to such an object when it grazes a planet, whether its spin is knocked off, whether surface material slides and collapses, how much internal strength it really has, is a question with plenty of models and almost no measurements.
You cannot build this experiment. Nobody can drag a several-hundred-metre asteroid to within a satellite's distance of Earth, and nature schedules it for 13 April 2029 instead. Observing the same object with the same instruments before and after the pass gives the first direct test of rubble-pile dynamics under a real tidal stress.
It matters for planetary defence too. If an object is ever found on a genuine collision course, deciding whether to nudge it or break it requires knowing how it is put together. DART supplied the impact experiment and Hera the forensic follow-up; Apophis is the third experiment, supplied by nature, and the one where nobody touches anything.
How to watch
Where you stand matters enormously. Europe, Africa and western Asia have Apophis high in the sky around closest approach, and from there a reasonably dark site is all you need for a naked-eye sighting. At third or fourth magnitude it is as bright as an ordinary constellation star, so the real task is knowing where to look before it arrives. From East Asia the circumstances at closest approach are unfavourable and a naked-eye view is not realistic.
Unlike an eclipse, there is no safety issue at all. You are looking at a faint point in a night sky, so no filter is involved, and binoculars simply make it easier. Do not expect a streak like a meteor: Apophis looks like a star, and that star creeps between the background stars over minutes. If you use a telescope, a low-power wide field beats magnification, and manual tracking beats a drive.
Exact timings and the sky track will be refined as the date approaches, and observatories worldwide are likely to publish detailed guides and carry it live. If you miss it overhead, the orbit replay on this page follows the geometry — the way the trajectory dives inside the satellite ring, bends sharply, and leaves on a changed orbit. That view arguably shows what is actually happening better than the sky does.
See this for yourself — replay the moment in the orbit view
Background
Apophis was found in June 2004 from Kitt Peak in Arizona, initially catalogued as 2004 MN4. For a few months afterwards the observational arc was thin and the computed impact probability for 2029 kept climbing, earning it a Torino Scale rating of 4 — still the highest ever assigned to any object. Then older images turned up in which it had gone unnoticed, the orbit snapped into focus, and the probability collapsed to zero.
That episode ended up improving how planetary defence works. Apophis is the case study for how a probability can spike and vanish as data accumulates, and for how that ought to be explained to the public while it is happening. Surveys for near-Earth objects and the follow-up networks behind them were both strengthened noticeably in its wake.
Apophis keeps returning after 2029, but the approaches in 2036 and 2068 are nowhere near as close. What follows instead is exploration. The spacecraft that delivered the Bennu samples, renamed OSIRIS-APEX, is due to reach Apophis just after the flyby, and ESA has been preparing a mission intended to arrive beforehand so the same object can be measured on both sides of the encounter. Schedules and details for both may still change.
FAQ
Is there any chance Apophis hits Earth?
No. Refined orbit solutions rule out an impact for at least the next century, including the 2068 return that stayed on the watch list longest. The 2.7% figure from 2004 came from an orbit based on a short observation arc, and it disappeared as more data came in.
Will it really be visible to the naked eye?
From Europe, Africa and western Asia, yes. Around closest approach it reaches roughly third or fourth magnitude, bright enough to see without equipment under a dark sky. Binoculars make its motion against the background stars far easier to notice. From East Asia the circumstances are poor.
Why will it not hit a satellite?
The geostationary ring is a thin band with its satellites spaced hundreds of kilometres apart, so the volume is effectively empty. With the trajectory known precisely, the collision risk is negligible. Operators will nonetheless track the pass closely.
Will the encounter change the asteroid itself?
Probably. Earth's tides are expected to perturb its spin state and may trigger landslides on the surface, but how much is exactly what nobody can predict with confidence. That is why a spacecraft is being sent to examine the object immediately afterwards.
Related
- OSIRIS-APEX arrives at Apophis
- DART — the first planetary defence test
- Hera arrives at Dimorphos
- Hera — object index
- Earth — object index
Times and figures are approximate — verify with official sources when planning travel. Simulation uses J2000 mean elements.