The mean radius of the sun is 432,450 miles (696,000 kilometers), which makes its diameter about 864,938 miles (1.392 million km).
The sun is the largest and the most massive object in the solar system, but it is just a medium-sized star among the hundreds of billions of stars in the Milky Way galaxy.
The sun is nearly a perfect sphere. Its equatorial diameter and its polar diameter differ by only 6.2 miles (10 km). The mean radius of the sun is 432,450 miles (696,000 kilometers), which makes its diameter about 864,938 miles (1.392 million km). You could line up 109 piles of earth across the face of the sun. The sun's circumference is about 2,713,406 miles (4,366,813 km).
It may be the biggest thing in this neighborhood, but the sun is just average compared to other stars. Betelgeuse, a red giant, is about 700 times bigger than the sun and about 14,000 times brighter.
"We have found stars that are 100 times bigger in diameter than our sun. Truly those stars are enormous," NASA says on its SpacePlace website. "We have also seen stars that are just a tenth the size of our sun."
According to NASA's solar scientist C. Alex Young, if the sun were hollow, it would take about one million Earth to fill it.