Introducing the ultimate, cosmic debunker of Flat Earth
We all know that the Earth is flat spherical in shape- but have you ever wondered why? I have! As a little kid, I used to believe that there was something special about a sphere itself- some mathematical beauty or symmetry that made it a popular choice for a planet shape. Turns out, it is a favorite shape, not of any human's but of gravity's- the sculptor of the universe!
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The shape of the Earth- a sphere [Note the vertical lines- they are called longitudes, while the horizontal, parallel ones are called latitudes] |
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| Platonic solids Why can't the planets be any of these shapes? |
Gravity-
Gravity is one of the four fundamental forces which govern the universe. It is generally understood as an attractive force, which causes all bodies with mass to be attracted toward each other, [Newtonian picture of gravity] but its picture has changed tremendously, with Einstein's theory of general relativity, where gravity is not so much an attractive force, but the geometry of spacetime.
Gravity’s role in shaping planets is as follows-
- A sphere is formed when an infinite set of points are equidistant to a single, central point. Since gravity attracts matter uniformly, during the formation of the solar system, gravity coalesced all of the blown away dust and debris in the protoplanetary system into Earth.
The universal law of gravitation [Newtonian Mechanics]
Image credit: Wikimedia
- However, magnitude of the force of gravity required to form a spherical shape depends on the amount of mass of a body. Thus, the minimum mass required to collapse a body into a spherical shape is 1/1000th of the mass of the Earth. [i.e. 5.972* 10^21 kg]
A young Earth
Image credit: National Geographic Channel
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Two asteroids- Ceres [the largest] and 433 Eros. |
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