If The Heliocentric Model Was True, And The Moon Was The Cause Of The Eclipse.
Why Is It Only Every 18 Months.
The Sun Is 93 Million Miles Away Right, The Moon Is Close Up Going Around The Planet Every Day Once a Day.
There Would Always Be A Shadow Of The Moon At Some Point On The Earth Every Single Rotation, Even If Just Partial.
Nothing About the Idea Of the Moon Being The Cause of The Eclipse Adds Up.
You Would Have Both Solar And Lunar Eclipses Way More Often Than 18 Months.