What directly correlates with crystal size in an igneous rock?

Cooling rates

Explanation:

The rate of cooling directly correlates with the crystal size in an igneous rock.

Crystal size of igneous rocks can be used to construe the way a melt cools.

When a melt cools rapidly, little to no crystal forms. The nucleation center becomes very small and therefore, the mineral sizes are in turn very fine. When a melt has enough time to cool, bigger mineral grains will crystalize. This is because nucleation centers have more time to develop.

Argon, carbon-14, and carbon-12

Why the planet stays in orbit is because of inertia (object stays in motion until a force changes it’s motion) also the atmosphere and gravity!