Check out this answer from Consensus:
Based on the current scientific understanding, it is not feasible for a planet to be flat. Gravitational forces naturally shape planets into spheres, and while rotation can cause some flattening, it is not enough to result in a flat shape. Theoretical models and observational data consistently support the spherical nature of celestial bodies.
The concept of a flat planet is often discussed in popular culture and pseudoscience, but it is important to examine this idea through the lens of scientific research. The shape of celestial bodies, including planets, is determined by a variety of factors such as gravity, rotation, and internal dynamics. This synthesis will explore the feasibility of a flat planet based on current scientific understanding.
Key Insights
- Gravitational Forces and Planetary Shape:
- Gravity naturally pulls matter into a spherical shape. This is because a sphere is the most efficient shape for minimizing potential energy in a gravitational field2.
- Rotational Effects:
- Planets that rotate experience centrifugal forces, which cause them to become oblate spheroids rather than perfect spheres. This flattening is minor and does not result in a flat shape2.
- Theoretical Models and Observations:
- Internal Structure and Dynamics:
- The internal structure and dynamics of planets, such as the Earth’s geodynamics, further support the spherical shape. Variations in density and internal pressure contribute to maintaining a roughly spherical form2.
Is it possible that a planet could ever actually be “flat”?
Yiannis Tsapras has answered Extremely Unlikely
An expert from Heidelberg University in Astronomy, Astrophysics, Physics, Cosmology
Objects massive enough to be classified as planets possess enough mass to ensure that after they have formed their shape will be approximately spherical. Comets and asteroids, on the other hand, often have bumpy irregular surfaces and may, in rare occasions, be approximately flat (e.g. Oumuamua).