Approximately 58 Earths can fit inside Neptune by volume. This is based on comparing their volumes, where Neptune's volume is about 6.25 × 10^13 km³, and Earth's volume is about 1.08 × 10^12 km³, making Neptune roughly 57.7 times the volume of Earth
. To summarize:
- Neptune's equatorial radius is about 24,764 km, nearly four times that of Earth's radius (~6,378 km)
- Using the volume formula for spheres, Neptune's volume is about 58 times that of Earth
- In terms of mass, Neptune is about 17 times more massive than Earth, but since volume scales with the cube of the radius, volume comparison gives the number of Earths that can physically "fit" inside Neptune
Thus, nearly 58 Earth-sized planets could fit inside Neptune if it were hollow and Earths were packed inside by volume.
