How many Earths would fit inside the sun if it were hollow?
—Jason Thornton, Chicago
The sun is the largest and most important star in our solar system. It has a diameter of approximately 865,000 miles, about 109 times larger than the Earth’s 8,000 mile diameter. An easy way to estimate how many Earths would fit inside a hollow sun would be to compare the volumes of the two spheres, which are related by the cubes of their radii. This means the interior of the sun would hold about 1.3 million Earths.
Dead space between the spheres would reduce the number of Earths to just under 960,000. The sun is only about average size when compared to other stars. A massive red giant star like Betelgeuse is about 700 times larger and more than 10,000 times brighter than the sun.