As far as stars go, our sun gets a lot of fanfare. Not only does life on Earth literally revolve around it, it dwarfs the rest of the stars in the sky — from our perspective, at least. But if you zoom out to the far reaches of our galaxy, the sun no longer looks like such a giant. In fact, it’s pretty average in size. So what is the largest known star in the universe?
The answer depends on whether you’re talking about mass or the total volume of a star — that is, how much space it takes up, said Phil Massey, an astronomer at the Lowell Observatory in Flagstaff, Arizona. The heaviest stars are often unremarkable when it comes to physical size, and the most voluminous stars are often lightweights. That’s because as stars get older, they tend to expand and shed mass. “It’s like talking about people,” Massey said, “The tallest people may not weigh the most.”
Let’s say you’re talking about mass. The record holder there is the star R136a1, Massey said. It’s located about 160,000 light-years from Earth in the Large Magellanic Cloud, a small galaxy that orbits the Milky Way. In diameter, this star is 30 to 40 times the size of our sun — picture a cherry next to a giant yoga ball that is more than 200 times more massive. This star is also relatively young — roughly 1 million years old compared with our sun’s 4.5 billion years — and “hasn’t done much cooling off or expanding,” according to Massey.
