These objects are tracked and are NOT on a collision course with Earth. “If it hits” is a hypothetical to show scale.
Near-Earth object · discovered 2004
99942 Apophis
The benchmark close approach of our lifetime. In 2029 Apophis passes inside the ring of geostationary satellites — closer than many of the things humans put in orbit.
77
watch score
How bigiEstimated from brightness and an assumed albedo. Radar or a spacecraft visit would tighten it.
335m
range 310–375 m
How closeiLD = lunar distance (~384,400 km). The closest the object's path brings it to Earth's centre.
0.08LD
range ≈31,600 km
How fastiVelocity relative to Earth at closest approach.
7.4km/s
range 7.3–7.5 km/s
CompositioniInferred from spectral type. Drives whether an impact would airburst or reach the ground.
Stony
range Stony (Sq-type)
If it hit — a scale comparison, not a forecast
How big is that, really?
Bus12 m
20-storey tower65 m
Stadium250 m
Eiffel Tower330 m
This object335 m
Impact energyiKinetic energy converted to TNT-equivalent, with the size and speed ranges propagated through.
386 Mt
range 298 Mt – 557 Mt
Where that sits
Hiroshima
Chelyabinsk
Tunguska
Tsar Bomba
An object this size would reach the ground and excavate a crater. The figures below are a scale comparison — Apophis is not on an impact trajectory.
During the 2029-04-13 pass it should be visible without optics from Europe, Africa & western Asia — a slow-moving "star" tracking across the sky over a couple of hours.