Asteroid Impact Energy Calculator Formula

Understand the math behind the asteroid impact energy calculator. Each variable explained with a worked example.

Use the Asteroid Impact Energy Calculator

Formulas Used

Asteroid Mass

mass_kg = (pi / 6) * pow(diameter, 3) * density

Impact Energy

energy_joules = 0.5 * (pi / 6) * pow(diameter, 3) * density * pow(velocity, 2)

Energy (megatons TNT)

energy_megatons = 0.5 * (pi / 6) * pow(diameter, 3) * density * pow(velocity, 2) / 4.184e15

Variables

VariableDescriptionDefault
diameterAsteroid Diameter(m)100
densityDensity(kg/m³)3000
velocityImpact Velocity(m/s)20000
massDerived value= (pi / 6) * pow(diameter, 3) * densitycalculated

How It Works

Asteroid Impact Energy

The kinetic energy of a spherical impactor:

KE = 0.5 × m × v²

where m = (π/6) × d³ × ρ (sphere mass)

  • d = diameter
  • ρ = density (rock: ~3000, iron: ~7800 kg/m³)
  • v = impact velocity (typical 15-25 km/s for near-Earth asteroids)

    • 1 megaton TNT = 4.184 × 10¹⁵ J. The Chicxulub impactor (~10 km) released ~10¹⁴ Mt.

    Worked Example

    A 100 m rocky asteroid at 20 km/s.

    diameter = 100density = 3000velocity = 20000
    1. 01Mass = (π/6) × 100³ × 3000 = 1.571e9 kg
    2. 02KE = 0.5 × 1.571e9 × (20000)²
    3. 03= 0.5 × 1.571e9 × 4e8 = 3.14e17 J
    4. 04≈ 75 megatons TNT (larger than any nuclear weapon tested)

    Frequently Asked Questions

    How big must an asteroid be to cause global damage?

    Roughly 1 km or larger. The Chicxulub impactor (~10 km) caused a mass extinction. A 100 m asteroid would devastate a city or region.

    What is a typical impact velocity?

    For near-Earth asteroids: 15-25 km/s. Long-period comets can hit at 40-70 km/s, greatly increasing energy.

    How often do large impacts happen?

    Tunguska-class events (~50 m): every few hundred years. Chicxulub-class (~10 km): every ~100 million years.

    Ready to run the numbers?

    Open Asteroid Impact Energy Calculator