Illustration: Elena Scotti (Gizmodo)
Giz AsksIn this Gizmodo series, we ask questions about everything from space to butts and get answers from a variety of experts.  

The modern age has brought one of the most nightmarish inventions in all of human history—the atomic bomb. These weapons harness the power of physics, releasing an immense amount of energy from a relatively small amount of mass to generate unfathomable fire, disease, and death. They have the power to end the world as we know it.

But despite our weaponry, it’s really only ourselves (and other life forms) that will receive the brunt of the damage. The Earth itself will remain an approximate sphere, 25,000 miles around. Humans simply don’t have the firepower to destroy the Earth itself. Technically.

Advertisement

On this week’s Giz Asks, we asked scientists about the limits of these weapons by answering, theoretically, how many nukes it would take to send the Earth spiraling off its orbit and into the Sun, and if that’s at all possible. We also talked about what the true impact of detonating the planet’s nukes could be.

Konstantin Batygin

Planetary Astrophysicist at Caltech.

Without being clever about it: All you would need to do is suddenly stop the Earth from moving. Then it just falls in.

Earth kinetic energy (Ed note: the energy of the Earth orbiting the Sun) equals half the Mass of the earth times its orbital velocity squared, around 1040 ergs. (Ergs is a unit of energy). The Yield from the starfish prime test was 1 megaton of TNT (around 1022 ergs). Taking the ratio, you find that you need 600,000,000,000,000,000 nuclear weapons.

Curiously, gravitational binding energy of the Earth (the Energy to counteract the gravity holding the Earth together) is 1039 ergs. So if you tried this experiment and amassed the necessary amount of weapons, you would have ~10 times the energy needed to explode the Earth. Pretty interesting.

Advertisement

Luke Dones

Senior Research Scientist (planetary science and space), Southwest Research Institute 

The kinetic energy of the Earth in its orbit is:

E = ½ mv2 = ½(6 x 1024 kg)*(30,000 m/s)2 or approximately 3 x 1033 Joules, where m is Earth’s mass and v is its velocity around the Sun.

The energy of a 1 megaton bomb is Ebomb = 4 x 1015 Joules.

To put the Earth into the Sun, you’d have to change the energy of its orbit by an appreciable fraction of its current energy, so you’d need roughly E/Ebomb = (3 x 1033)/(4 x 1015) bombs, or roughly 1018 megaton bombs, i.e., a billion billion big bombs. This calculation assumes all the energy of the bomb goes into pushing on the Earth, which is unrealistic. So the number of bombs needed is probably even bigger than that.

Advertisement

Janine Krippner

Volcanologist, Postdoctoral Researcher, Concord University, West Virginia

If the largest and most explosive volcanic eruptions on Earth didn’t send us towards the Sun then I am pretty doubtful. I have seen estimates of eruptions being the energy equivalent of hundreds to thousands of times the energy of the bomb that devastated Hiroshima, and that is not taking into account the largest (very rare!!) eruptions from volcanoes like Yellowstone or Taupo.

Advertisement

Alan Robock

Distinguished Professor Department of Environmental Sciences, Rutgers University

I have no expertise in changing planetary orbits. But your proposition seems impossible to me.

However, I do have expertise on how the use of nuclear weapons in war could change climate. Please see this and this for more information, and watch my TEDx talk or Brian Toon’s. When cities and industrial areas are targeted, the explosions would start fires. The smoke from the fires would go up into the stratosphere above the weather, and would last for years. It would block out the Sun, making it cold, dark, and dry at Earth’s surface, while also destroying ozone and allowing more UV to reach the surface. The amount of climate change and UV would depend on the number of weapons, their targets, and how large the weapons are. We have calculated that a war between the US and Russia would produce nuclear winter, killing most agriculture on Earth and sentencing most people to starvation, and this theory has been validate with recent calculations. Even a war between two new, small nuclear powers like India and Pakistan, could produce climate change unprecedented in recorded human history, threatening billions with starvation.

Advertisement

Dr. Laura Grego

Senior Scientist, Global Security Program Union of Concerned Scientists

Here’s what nuclear weapons are really meant for. (Sorry, but it’s awful.)

The United States and Russia own the vast majority of nuclear weapons, each deploying around 2,000 and keeping another 2,000 in storage. One in five people live in one of the 436 cities with a population greater than one million, and so a large percentage of the world population could be wiped out using less than half of one country’s deployed nuclear weapons.

But even a nuclear conflict at a much smaller scale could have devastating effects. A conflict between India and Pakistan that resulted in 100 Hiroshima-sized nuclear bombs being used on large cities would kill about 20 million people outright. A report by the Physicians for Social Responsibility estimates that the smoke it would create would be carried up into the atmosphere, affecting the climate and patterns of precipitation for a decade. This could cause massive famine, leaving a billion or more people at risk of starvation. Keeping weapons with this capability is inhumane and unconscionable. It’s really time to find our way out of this mess and get rid of them.

Advertisement

Do you have a burning question for Giz Asks? Email us at tipbox@gizmodo.com.