ever wondered why every planet we know about is shaped like a sphere? Why not a
cube, or a triangle or an hourglass? While those—and let’s be honest, most
other shapes—would definitely break the laws of physics, there’s one odd planet
form that wouldn’t: a donut.
the shape of a donut, or toroid, as it’s called in mathematics, could
technically exist, but it would have to jump some steep physics hurdles to get
there. Planets are round because gravity pulls inward. To keep the hole, or
hub, at the center of a toroid planet from collapsing, you’d need an equal
outward force. Centrifugal force (the force you feel when a spinning
merry-go-round nearly sends you flying) could do the trick, but it would mean
that the planet would have to rotate at an extremely high rate. That would most
likely make a day on a donut-shaped planet last just a few hours.
would also do funny things to gravity. That centrifugal force would make
gravity the weakest at the equator (which, by the way, it is on Earth too).
Gravity would be strongest just inward from the poles. But unlike the minor
differences in gravity on Earth, these differences would be massive: more than
twice as much near the poles as at the equator. That means a vacation to the
tropics would come with instant weight loss — a pretty good deal. But don’t
pack your bags just yet: remember that high rotation rate? It would make for
harsh weather. We’re talking intense winds, zoned climates with massive
temperature differences, and small, super-strong storm systems.
about how a theoretical planet could form tells you a lot about your own
planet. Who knew that Earth’s sphere shape is why gravity is mostly the same
all over, and its 24-hour rotation is why the weather is relatively pleasant?
Of course, there’s another reason imagining a donut-shaped world is worthwhile:
it’s just plain cool.