If you've ever wondered why large planets and moons are round but smaller asteroids are irregularly shaped, the answer you're looking for lies within a concept known as the 'potato radius'.
The potato radius is a fascinating threshold in astronomy that marks the size at which an asteroid's gravity begins to dominate its shape.
SQUIRREL_13162421
Smaller space rocks remain lumpy and irregular, resembling potatoes.
However, once an object grows to a radius of about 200–300 kilometres, its self-gravity becomes strong enough to pull the rock into a more spherical shape, smoothing out its irregularities.
Ceres, for example is both a dwarf planet and an asteroid, residing as it does in the main asteroid belt between Mars and Jupiter.
But unlike other asteroids, it's spherical, and this is because its radius is 473km, more than large enough for gravity to influence its shape into becoming round.
And so, the potato radius marks the transition from asteroid-like objects to planet-like ones in appearance.
This concept is a reminder of how gravity shapes the Universe on every scale.
The potato radius is a quirky yet powerful illustration of how an object's size determines its behaviour and appearance in the vastness of space.
This article was taken from Big Ideas Little Pictures and Sketchplanations by Jono Hey.
