The cosmos contains objects spanning an astonishing range of sizes, from tiny fragments to the immense sphere of the Sun that dominates the entire solar system. Considering a small, distant body like Pluto next to the colossal Sun offers a classic thought experiment in astronomy. Asking how many Plutos could fit inside the Sun helps bridge the gap between abstract numbers and a comprehensible picture of cosmic dominance.
Comparing the Sizes of the Sun and Pluto
The vast difference in size between the two bodies provides the starting point for this calculation. The Sun, an average yellow dwarf star, has a mean radius of approximately 695,700 kilometers. This enormous dimension means that it accounts for over 99.8% of the total mass in the entire solar system.
In stark contrast, Pluto, classified as a dwarf planet, is a relatively small body orbiting in the distant Kuiper Belt. Its mean radius is estimated to be about 1,188 kilometers, which is less than 0.2% the size of Earth’s radius. To determine how many Plutos can be contained within the star, scientists must compare their volumes, not simply their diameters.
The Mathematical Calculation of Volume Capacity
Determining the number of Plutos that could occupy the Sun relies on comparing the volume of two spheres. The volume of any spherical object is calculated using the geometric formula \(V = \frac{4}{3}\pi r^3\), where \(r\) is the radius. Since both the Sun and Pluto are roughly spherical, the calculation simplifies to finding the ratio of their radii and then cubing that result.
The Sun’s radius is roughly 585 times larger than the radius of Pluto. Cubing this radius ratio reveals the staggering volumetric difference between the star and the dwarf planet. Based on their current estimated dimensions, the Sun has enough volume to contain approximately 190 million Plutos. This number is reached by dividing the Sun’s volume by Pluto’s volume, assuming the dwarf planets could be perfectly liquefied to fill all the available space.
This calculation highlights the immense volumetric scale of a star compared to the small, icy objects that orbit it. Even for a star considered average, its size utterly dwarfs the minor bodies that share its gravitational influence.
Understanding the Scale: Pluto Versus Earth and Jupiter
To grasp the magnitude of the 190 million figure, it is helpful to place Pluto’s size in context relative to more familiar worlds. Pluto is significantly smaller than Earth’s Moon. Its volume is less than one percent of the volume of Earth, making it a tiny world in the solar system.
This smallness is particularly clear when comparing the Sun’s capacity for Earths. The Sun could hold approximately 1.3 million Earths, assuming the planets were liquefied to eliminate any gaps between them. This 1.3 million figure is the typical baseline used to illustrate the Sun’s size.
The fact that the Sun can hold 1.3 million Earths, but over 190 million Plutos, illustrates just how small the dwarf planet is compared to the major planetary bodies. Even Jupiter, the largest planet, could fit inside the Sun about 1,000 times. The staggering number of Plutos illustrates the star’s volumetric dominance.