You might think all planets are perfectly round, like balls in space. And you’d be mostly right! It’s a fundamental characteristic of planets: they have enough mass to pull themselves into a spherical shape due to gravity. But just like a spinning top, planets aren’t always perfect spheres.
Think of our own Earth. It bulges slightly at the equator, thanks to centrifugal force – the outward push created by its spinning. While this bulge is subtle on Earth, it can be much more dramatic on planets with faster rotations. Imagine a planet spinning so fast that its poles become flattened, giving it a squished, football-like shape. That’s the power of centrifugal force!
And then there are the effects of the host star. If a planet is close enough to its star, the star’s gravitational pull can literally stretch and deform the planet. A good example is the exoplanet WASP-103 b, a gas giant twice the size of Jupiter. It orbits a star incredibly close, causing it to become ‘tear-shaped.’
This deformation can even impact the planet’s rotation. If the bulge towards the star isn’t always in the same place as the planet rotates, it takes a lot of energy. This leads to a fascinating phenomenon called tidal locking, where the planet always shows the same side to its star, just like our Moon always faces Earth.
WASP-103 b’s fast orbit further contributes to its squished shape, making it an incredibly flattened planet. While it may not be perfectly spherical, it’s still mostly round!
But hold on, there’s a wild hypothetical scenario – the toroidal planet. Imagine a planet spinning so fast that its centrifugal force completely overwhelms its gravity, making it shaped like a donut! This idea is more sci-fi than science, and no one has ever observed such a planet. Still, it’s a fascinating thought experiment that showcases the immense forces at play in the universe.
