The mushroom cloud resulting from the nuclear weapon test Bravo (yield 15 Mt) on Bikini Atoll. The test was part of the Operation Castle in 1954, and was one of the strongest (but not THE strongest) Hydrogen bombs ever detonated. In a hydrogen bomb explosion, nuclear fission compresses an internal pellet, which then undergoes nuclear fusion in a runaway, energy-releasing reaction. For some brief moments, the temperatures in there can exceed those in the center of the Sun. (U.S. DEPARTMENT OF ENERGY)

Ask Ethan: How Can A Nuclear Bomb Be Hotter Than The Center Of Our Sun?

The center of our Sun tops out at 15 million K, but nuclear bombs can get nearly 20 times hotter. Here’s how.

In terms of raw energy output, nothing on our world compares to our Sun. Deep inside our Sun, nuclear fusion transform enormous quantities of hydrogen into helium, producing energy in the process. Every second, this fusion causes the Sun to burn through 700 million tons of fuel, much of which gets converted into energy via Einstein’s E = mc². Nothing on Earth can compare to this amount of energy. But in terms of temperature, we’ve got the Sun beat. That puzzles Paul Dean, who asks:

[T]he temperature in the core of our sun is usually cited at 15 million degrees Celsius or so. […] What I don’t get is this: some mid-sized thermonuclear test detonations done by the old Soviet Union and the USA have been recorded at (if only very briefly) 200 or even 300 million degrees Celsius. How can our pithy 3 stage hydrogen bomb blasts be so much hotter than the dense hell of the Sun’s monster fusion oven?

It’s a great question with a fascinating answer. Let’s find out.