The sheer scale of the cosmos often challenges comprehension, making it difficult to visualize the size difference between celestial bodies. Even objects within our own solar system, like the dwarf planet Pluto and the central star, the Sun, are separated by a vast gulf in size. To help grasp this disparity, a useful exercise is determining how many times the volume of the smaller object can fit inside the larger one. This comparison highlights the enormous volumetric capacity of our star and provides the precise number of Plutos that could be contained within the Sun.
The Dimensions of Pluto and the Sun
Understanding the relative sizes of these two objects begins with their physical dimensions, specifically their radii. The Sun is a colossal sphere of plasma with an average radius of approximately 695,700 kilometers. By contrast, the dwarf planet Pluto is a tiny, icy world located in the Kuiper Belt, with a radius of 1,188 kilometers. Pluto is significantly smaller than even Earth’s Moon. To calculate the volume of any near-spherical body, scientists use the formula \(V = \frac{4}{3}\pi r^3\).
Calculating the Volume Ratio
Determining how many Plutos fit inside the Sun requires dividing the Sun’s total volume by Pluto’s total volume. Because both bodies are nearly spherical, this volume ratio can be calculated by simply cubing the ratio of their radii. The final result of this division shows that approximately 200 million Plutos could be packed inside the Sun. This number, 200,000,000, represents the massive volumetric dominance of the Sun over the small dwarf planet. For this calculation, astronomers assume that both the Sun and Pluto are perfect spheres, which simplifies the geometry for an accurate comparison of their intrinsic volumes.
Putting the Scale into Perspective
Translating a number like 200 million into a relatable concept requires comparing it with more familiar objects. For instance, the Sun is so large that it could contain about 1.3 million Earths within its volume. The volume of Pluto is less than one-third of the volume of Earth’s Moon. If the Sun were a large sports stadium, a single Pluto would be smaller than a grain of rice inside that stadium. The number of Plutos needed to fill the Sun underscores the fact that the star holds nearly 99.9% of all the mass in the entire solar system.