The question of how many nuclear weapons it would take to destroy the Moon is a thought experiment moving from military speculation into fundamental physics. It highlights the immense scale difference between humanity’s most destructive technology and the natural forces governing celestial bodies. Calculating this requires defining what “destruction” means for an object held together by gravity. This exercise compares the colossal energy stored within the Moon to the output of our largest terrestrial explosions.
Defining Planetary Destruction: Gravitational Binding Energy
To “destroy” a celestial body, fracturing its surface is insufficient; fragments would re-accrete due to mutual gravity. True destruction requires overcoming the object’s self-gravity so that all constituent pieces disperse permanently into space. This minimum energy threshold is the Gravitational Binding Energy (GBE).
The GBE represents the total energy needed to separate every particle until they are infinitely far apart. To achieve this, every particle must be accelerated past the Moon’s escape velocity, ensuring the fragments fly off and the Moon is truly dispersed.
This binding energy measures the work done by gravity in assembling the object. For any self-gravitating sphere, the GBE is proportional to its mass squared and inversely proportional to its radius. Overcoming the GBE is the lower limit for eliminating a planet or moon.
If the Moon were cracked into two halves, the gravitational attraction between those massive pieces would remain enormous. They would either spiral back together or orbit as a binary system. The energy required to overcome the GBE dwarfs the energy needed for fragmentation, making GBE the standard metric for total celestial destruction.
Calculating the Energy Requirement: The Moon’s Mass and Scale
Calculating the Moon’s Gravitational Binding Energy requires using its physical measurements. The Moon has a mass of approximately \(7.35 \times 10^{22}\) kilograms and a mean radius of about 1,737 kilometers. These figures determine the scale of the energy needed for dispersal.
The calculated Gravitational Binding Energy for the Moon is approximately \(1.24 \times 10^{29}\) Joules. For perspective, the total annual energy consumption of human civilization is estimated around \(5 \times 10^{20}\) Joules. The energy required to scatter the Moon is over 200 million times greater than all the energy currently used on Earth annually.
This figure can be compared to natural cosmic events. The impact that created the Caloris Basin on Mercury, a 1,500-kilometer crater, released an estimated \(1.3 \times 10^{26}\) Joules of energy. This force is only about one-thousandth of the energy required to unbind the Moon, demonstrating that the Moon’s mass and gravity demand an energy input far beyond what is normally observed in the solar system.
To match the Moon’s GBE, one could compare it to the Sun’s total energy output, which releases energy at a rate of \(3.8 \times 10^{26}\) Joules every second. If humanity could harness and redirect the Sun’s power, it would take roughly 326 seconds—just over five minutes—of the Sun’s full energy production to achieve the Moon’s dispersal energy.
The Scale of Nuclear Power: Comparing Weapons to Cosmic Forces
Against the backdrop of planetary physics, the most potent weapons ever created appear minuscule. The standard unit for measuring the destructive power of nuclear weapons is the megaton (MT) of TNT. The most powerful nuclear device ever detonated was the Soviet Tsar Bomba, which had an official yield of 50 megatons.
When converted to Joules, one 50-megaton Tsar Bomba releases approximately \(2.1 \times 10^{17}\) Joules of energy. This is an astounding amount of energy in a terrestrial context, capable of leveling cities. However, comparing this yield to the \(10^{29}\) Joules required for lunar destruction reveals a vast difference.
The comparison shows a twelve-order-of-magnitude difference between the largest human-made explosion and the Moon’s gravitational resistance. A single Tsar Bomba’s energy output is closer in scale to a small asteroid impact than to the forces that bind a celestial body. This illustrates the gap between military power and cosmic forces.
The energy release of a nuclear weapon is instantaneous and localized. Even a 50-megaton blast is negligible when viewed against the total mass of the Moon. Natural cosmic forces, such as the continuous energy output of the Sun, operate on entirely different scales of magnitude and duration than any man-made weapon.
The Final Count: Why the Number is Impractically Large
Comparing the Moon’s required Gravitational Binding Energy (\(1.24 \times 10^{29}\) Joules) to the Tsar Bomba’s yield (\(2.1 \times 10^{17}\) Joules) determines the final count. It would take nearly 600 billion nuclear devices of that size to theoretically match the energy required for the Moon’s permanent dispersal. This number is far beyond current human capability.
This calculation is purely theoretical, based on the perfect application of energy. The physical act of detonating them presents insurmountable obstacles. Nuclear explosions are inherently inefficient for this purpose because they are surface phenomena, while the gravitational binding force acts throughout the entire volume of the Moon.
To maximize the effect, billions of weapons would need to be precisely drilled and placed deep within the Moon’s core, which is logistically impossible. The energy from an explosion disperses inefficiently in a vacuum and the Moon’s subsurface, wasting much of the blast energy as heat.
The localized nature of fusion energy release cannot overcome the uniform, global force of gravity permeating the celestial body. Even if humanity could deliver the required hundreds of billions of weapons, the physical mechanics of the detonation would prevent the energy from being effectively applied to unbind the Moon.