Are the heavens moving or are we?

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In the previous series of posts, we discussed about the key role that a rotating earth plays in space shuttle launches and quickly skimmed through why the earth began to rotate in the first place.

But in the 21st century, there are many experiments  (Coriolis effect,  Foucault’s pendulum ,etc, etc) that you can do to convince yourself that the Earth is indeed rotating.

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                                             ISS Live Stream

But back in the days of Galileo it was still debatable whether Earth was rotating or not. 

Why does a ball thrown straight up in the air fall to the same place on the ground ?

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One
of the profound Aristotelian arguments against the rotation of the
Earth was that if the Earth were rotating, a thrown ball/arrow would not
land in the same place that it was thrown.

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This was believed so
because, by the time the projectile traverses its path the Earth would
have moved by a certain distance. Hence, the ball would never land at
the same place it was thrown.

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Take a second to think about this. Can you come up with an argument against this rationale ?

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Here
is an excellent argument given by Galileo in favor of the rotation of
the Earth and why things would still fall to the same place even if the
Earth were rotating:

In replying to this, those who make the earth movable answer that the canon and the ball which are on the earth share its motion or rather that all of them together have the same motion naturally.

Therefore the ball does not start from rest at all but to its motion about the center joins one of projection upward which neither removes not impedes the former.

You
will see the same thing by making the experiment on a ship with a ball
thrown perpendicularly upward from a catapult. It will return to the
same place whether the ship is moving or standing still

The profundity of this argument is that, the very same principle that ‘ball does not start from rest at all  but with velocity of the earth’ is used by space shuttles to reach orbital velocity with lesser fuel consumption.

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But despite Galileo’s argument, it was still believed for a long time that it were the heavens that moved and not the earth.

For
God hath established the world which shall not be moved in spite of
contrary reasons because they are clearly not conclusive persuasions.

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