A Serious Study During the Cold War#

Back when the Cold War was a big deal, the moon wasn’t just for exploration. It was seen as a potential spot for military bases. The US Air Force even ordered a proper study to figure out what a nuclear bomb would actually do if it went off on the lunar surface.

Our Imaginary Experiment#

But let’s not just quote old studies, that’s a bit dry. Let’s run our own little science experiment, shall we? Imagine we have a super powerful 100 Megaton thermonuclear Warhead. That’s about twice as strong as the most powerful bomb ever set off here on Earth. We’ll even put a few curious astronauts nearby as observers (don’t worry, this is just pretend).

Alright, ready? Let’s push the button… and slow down time.

The First Moments#

For the first few tiny fractions of a second, you wouldn’t see much happening outside the weapon itself. Inside, though, things are insane. Powerful explosives compress a special radioactive metal core so much it goes critical, kicking off a nuclear fission chain reaction.

This creates incredibly hot stuff, a plasma reaching 100 million degrees Celsius! This first stage then triggers the second stage, where atomic bits start fusing together, just like they do in the middle of a star. For a brief instant, our bomb holds one of the hottest spots in the whole universe.

Only about 10 milliseconds later does the rest of the universe even notice something’s happened. Suddenly, the bomb basically disappears, and a bright, fiery ball of nuclear energy is born.

The Big Difference: No Atmosphere#

So far, it sounds like a giant explosion, right? But what happens next is totally different from an explosion on Earth, and it’s all because of one major thing: there’s no atmosphere on the moon.

As the fireball glows intensely, it shoots out a flash of X-rays and thermal photons. Think of it as a silent wave of heat blasting outwards in every direction.

• On Earth: This kind of heat would char and burn everything within maybe a 50 km radius, minimum.
• On the Moon: Without any air or oxygen, there’s no burning at all. Plus, there’s nothing really to burn anyway.

The moon’s surface is mostly crunchy dirt made of silicate rock and metals, ground down over billions of years by meteorite hits. It’s mixed with just tiny bits of water.

When the explosion’s heat hits this lunar dirt:

• X-rays from the fireball instantly vaporize a thin layer of rock right off the surface, turning it into gas.
• Any unlucky dust caught actually inside the fireball gets so hot it melts into glass.
• Any astronauts watching from within about 50 km of the blast? Yeah, they’d be fried.

No Shock Wave#

Here’s another massive difference between space explosions and Earth ones.

• On Earth: The atmosphere pushes back hard against the expanding blast. The air pressure stops the fireball’s outward rush really quickly. But this isn’t good! When the fireball smashes into the atmosphere, it creates the most destructive part of a nuclear blast on Earth: the shock wave. This is super-compressed air rushing out faster than sound, shattering buildings and making a roar loud enough to burst your insides.
• On the Moon: There is no atmosphere. No shock wave. Nothing gets in the way of the expanding explosion. The fireball just grows bigger and bigger in complete silence. There’s no air to stop it or give it a voice.

It would actually look amazing from a safe distance. Problem is… there’s hardly any safe distance.

Radiation Danger#

Without an atmosphere to soak up or weaken the deadly ionizing radiation (the stuff that messes up your DNA), anyone close enough to get a good look at the expanding silent fireball would be hit with fatal amounts of radiation.

The Moon Smashes Back (Kind Of)#

But wait, there’s more! While all this is happening, the force of the explosion slams into the moon itself. About a tenth of the explosion’s massive energy gets turned into seismic waves, causing an intense moonquake.

The moon is way smaller than Earth, so our pretend astronauts would feel a violent shaking no matter where they were standing – nowhere to run, nowhere to hide from it. It would feel like an earthquake registering about 7 on the Richter scale.

This shaking could seriously damage or completely flatten any buildings or infrastructure we might have built on the moon. If the blast happened on the side of the moon facing away from you, you wouldn’t even know it was a bomb; the shaking would just feel like a really big asteroid, maybe the size of the Great Pyramid, had just hit somewhere.

Cratering and Debris#

Right where the bomb went off, the ground wouldn’t just crack; it would splash upwards, kind of like when you throw a rock into a pond.

The explosion’s force pushing down could dig out as much as 100 million cubic meters of dust and rock, forming a crater about 1 kilometer wide. The solid bedrock underneath would be turned into rubble.

All this excavated stuff is shot upwards and outwards in every direction. Again, with no atmosphere, there’s nothing to slow it down. Lots of this debris never even falls back to the moon! It flies off faster than the moon’s escape velocity, heading out into the solar system.

This creates a swarm of micrometeorites cast off into space. While few of these would be bigger than pebbles by the time they might rain down on Earth, they could happen.

• Any satellite, astronaut, or space station in their path, however, would have a really bad time.
• These micrometeorites are launched at all sorts of speeds and angles, spreading across the entire surface of the moon like bullets. They’d punch right through our curious astronauts no matter where they thought they were standing.

No Mushroom Cloud, Just a Fade#

Finally, the explosion starts to die down.

• On Earth: The hot fireball rises like a giant hot air balloon, forming that familiar stalk shape as it pulls in cooler air. The top rounds out, creating the classic mushroom cloud.
• On the Moon: You know the drill by now: no atmosphere, no mushroom.

The huge plasma bubble just gets bigger and cooler, losing the energy needed to do exciting (or terrifying) things. Within seconds of the trigger being pulled, the bubble turns redder and just fades away from view.

From Earth, you might see it like a new star flickering on for just a moment, only to disappear again right away. A quick spark, then nothing.

As the cloud of tiny debris reaches high above the moon’s surface, it would be lit up by the sun for a few minutes, looking oddly beautiful to anyone left alive to see it.

The Moon’s Orbit and Long-Term Impact#

What about knocking the moon closer to Earth or off course? Don’t worry. Trying to move the moon with a nuclear bomb is like trying to push a truck by blowing on it. Nuclear explosions feel huge to us, but space is way, way bigger. Our mighty hypothetical blast just leaves another crater on the moon, one among millions already there.

However, anyone on the moon would continue to have a bad time.

• The material that eventually rains back down onto the moon is radioactive.
• With no wind, rain, or processes to wash it away or bury it, the moon’s surface would stay contaminated.
• Fortunately, the worst of the radiation would decay down to levels similar to the natural radiation from cosmic rays in about one year.

Conclusion#

So, here’s the takeaway: The moon itself? It basically doesn’t care about being nuked. It would barely notice in the grand scheme of things, just getting another dent.

But using the moon as a place to set off a nuclear test? Yeah, that pretty much ruins it for everyone trying to live or build anything useful up there.

So, maybe… let’s just not do that.