Astronomers finally know why the first documented supernova was super-sized.
The exploded star was observed by the ancient Chinese in the year 185, and visible for eight months. It was later found to be a bigger-than-expected supernova remnant, 8,000 light years away. Each light year is about 6 trillion miles.
New observations in the infrared show the explosion took place in a cavity in space. The cavity allowed the stellar shrapnel to shoot faster and farther out into the universe.
The star — similar to our sun — died peacefully and turned into a dense white dwarf. It sucked up material from another star, and then exploded in a supernova.
NASA announced the findings Monday. Four space telescopes were used in the study.