Nuclear fusion

That's six times as hot as the center of the sun and a major breakthrough for nuclear fusion.

Being able to control plasma that is hotter than the Sun is notoriously difficult.

Nuclear fusion takes place in the center of stars, but scientists are also attempting to reproduce it on Earth in the hopes of creating a clean and essentially unlimited power source that could replace fossil fuels.

Nuclear fusion isn't very efficient without the incredibly hot temperatures found on the sun.

"Finding a star can at times be harder than finding a planet."

Scientists may have solved one major problem that comes up when building a fusion reactor—runaway electrons.

Pyongyang has tested something, but it's unlikely to be a full-blown H-bomb.