How many Earths fit in the Sun, by volume

NASA's Sun fact sheet gives the exact ratio of the Sun's volume to Earth's, and it is a number with seven digits. The Sun's average radius is 695,700 kilometers, which is 109.2 times Earth's. This page shows how that answer is built, one step at a time, without spoiling it before the clip does.

The clip climbs a ladder of sizes. About 49 Moons would fit inside Earth, using NASA's Moon-to-Earth volume ratio of 0.0203. Jupiter, the biggest planet, could hold 1,321 Earths. The Sun holds about 987 Jupiters. Multiply the last two steps together and you reach, within rounding, the figure NASA reports in a single step.

Width and volume behave differently. The Sun is 109.2 times wider than Earth, but volume grows with the cube of width. Cube 109.2 and you land on that same figure again. That is why a star that looks only about a hundred times bigger across has room for so many planets.

Volume is not weight, though. NASA says it would take more than 330,000 Earths to match the Sun's mass, and its fact sheet gives the ratio as 332,900. That is far fewer than the number that fill its volume. Divide the mass ratio by the volume ratio and the Sun's average density comes out at about a quarter of Earth's. Even so, the Sun holds 99.8 percent of the solar system's mass, NASA says.

How it was counted: the headline figure is a volume ratio from NASA's planetary fact sheets, the Sun sheet last updated on 9 May 2024. It treats Earth as if it could be poured into the Sun with no gaps. Real, round Earths would leave gaps between them, so fewer whole planets would fit. The Moon and Jupiter ratios come from the same NASA tables. The figure of about 987 Jupiters is our own division of NASA's Sun volume by its Jupiter volume.

Universe Today divides the two volumes itself and reaches the same answer as NASA, so the number does not depend on a single page.