Asteroid impact simulator

Drop a body of stone, iron, ice or loose rubble on any point on Earth and see the crater it digs, the fireball it makes and how far the shock wave breaks windows.

Open the asteroid impact simulator

What this simulator does

Choose a diameter from 1 metre to 3 kilometres and a material — stone, iron, ice or a rubble pile like Bennu — then click anywhere on the map. The body arrives at the entry speed you set, 17 km/s by default and 12.7 km/s for the Bennu preset, its kinetic energy is converted into megatons of TNT, and the simulator draws what that energy does to the ground:

Crater — the hole, if the body survives the atmosphere
Fireball — the radius where essentially nothing survives
20, 5 and 1 psi blast rings — reinforced buildings destroyed, houses collapsed, windows shattered
Severe burns — the radius where thermal radiation causes third-degree burns

Every town inside those rings is counted one by one from OpenStreetMap, and the site estimates deaths per zone.

The simulator dropping a 140-metre stone asteroid on New York: crater and fireball at the centre, three blast rings around it, result panel reading 3.6 million killed — A 140-metre stone body over New York — the size that arrives roughly once every 20,000 years. Bright centre: crater and fireball. Wider rings: 20, 5 and 1 psi of overpressure.

Most meteors never reach the ground

This is the part casual impact calculators get wrong. Small bodies break up under the pressure of entry and detonate in the air, and the simulator models it:

Stone under about 70 m bursts in the air
Iron under about 20 m
Rubble pile under about 90 m
Ice under about 150 m

When that happens there is no crater, the height of the burst weakens the heavy damage directly below it, and most of the energy goes into a shock wave that breaks glass over a wide area. The 20-metre Chelyabinsk body burst about 30 km up in 2013: no crater, no deaths, and roughly 1,500 people injured — almost all of them by flying window glass while they stood watching the fireball.

Why iron behaves so differently

Iron is 2.6 times denser than stone, so a body of the same size carries 2.6 times the energy and is far more likely to survive the atmosphere intact. The comparison is in the ground:

An iron body about 50 m across dug Meteor Crater in Arizona — 1.2 km wide, still there after 50,000 years.
A stone body of similar size exploded over Tunguska in 1908, flattened 2,000 km² of forest and left no crater at all.

Ice is light and fragile, which is why the threshold is so much higher — a comet fragment has to be enormous before it reaches the ground.

A 20-metre meteor over Chelyabinsk in the simulator, showing an airburst with no crater and a wide ring of shattered windows — The 2013 Chelyabinsk body at 20 m. No crater at all: it burst high in the air, and what is left is a broad ring of broken glass.

Scenarios worth trying

20 m stone over Chelyabinsk — the 2013 event, an airburst with no crater
60 m stone over Tunguska — 1908, but see what it does over a city instead
50 m iron in Arizona — the body that actually made a crater
140 m stone on New York — the size that arrives roughly once every 20,000 years
3 km on Chicxulub — a tenth of the dinosaur killer, and already off the scale

How likely is any of this?

Small bodies burst in the sky every year, almost always over ocean or empty land. Objects around 140 m across — the size that would destroy a region rather than a city — arrive roughly once every 20,000 years. City-killers larger than that are rarer still, and no known asteroid is on course to hit Earth this century.

NASA and ESA track near-Earth objects continuously, and in 2022 the DART mission deliberately changed an asteroid's orbit by hitting it, which makes this the one hazard on this site that humanity can currently do something about.

What the model leaves out

Entry angle, which changes the crater shape and can spread the damage into an ellipse. Ocean impacts, which trade the crater for a tsunami — for that, run the tsunami simulator separately. Global effects: an impact large enough to fill the sky with dust kills far more people through failed harvests than through blast, and none of that is modelled here. Blast radii scale with the cube root of energy, which is the standard approximation and holds well for the range this tool covers.

Questions

What is the difference between a meteor, a meteorite and an asteroid?

An asteroid is the rock in space. A meteor is the streak of light it makes burning through the atmosphere. A meteorite is what is left when a piece reaches the ground. This simulator covers all three stages of the same object.

Why is there no crater for my meteor?

Because it burst in the air. Raise the diameter above the threshold for its material, or switch to iron, and the crater appears.

Why are the death tolls so much lower than for a nuclear weapon of the same yield?

Because impacts give off far less of their energy as heat. A nuclear explosion releases about a third of its yield as thermal radiation; an impact releases only a few per cent, so the burn radius is much smaller for the same megatonnage.

Can I simulate an ocean impact?

You can drop one on water, but the model draws blast and thermal rings, not the wave. The wave is a separate tool.

Further reading: What an asteroid impact does, size by size