How do the positions of the Earth, moon, and sun contribute to eclipses?

The moon passes directly passes between the earth and the sun, as the sun is covered by the moon's shadow, it wil actually gets cooler outside

The Moon's Two Shadows. An eclipse of the Sun (or solar eclipse) can only occur at New Moon when the moon passes between Earth and Sun. If the Moonshadow happens to fall upon Earth's surface at that time, we see some portion of the Sun's disk covered or 'eclipsed' by the Moon.