Question

For a planet whose moon orbits the planet in exactly the same plane as the planet orbits its sun, how often does that planet experience a solar eclipse

Answer 1

A solar eclipse occurs when the moon passes between its host planet and the sun. If the moon's orbit is on exactly the same plan as the planets orbit with the sun, then the moon would pass between the planet and the sun every time it completed a full revolution. Thus, a solar eclipse would occur every lunar month.