In case you didn’t, know, the sun is bigger than the earth. Yes, form here, the sun looks like its no bigger than the moon. But that’s because of how far away it is from the earth. 150 million kilometers to be exact. So how big is the sun? The sun’s radius is 695700 km. The earth’s radius is 6371 kilometers. That’s a huge size difference. The sun is so big, that 1.3 million earths could fit inside it, and it makes up 99.86 percent of the total mass of our solar system. So, in short, the sun is really big. But lets imagine for a second, what would our solar system be like if the earth were bigger than the sun?