With a hypothetical system, where the moon would be always on the opposite side of the planet than the sun, in a way that the moon would only be visible at night on the planet.
I don't know if this is possible, but if it was possible how they would behave. For example, I think that if this being possible, maybe at dusk/dawn both moon and sun would appear on the horizon at opposite sides.
And the last thing, could this system have a periodic event where both star and satellite would appear entirety above the horizon line.
Another thing I am not sure, is if the place at the planet would affect this, but if it doesn't matter I can work with both scenarios.
Is there any way to calculate how a planetary system would behave, where the satellite and the star appear simultaneously in the sky only once a year?
I'm writing a novel where this day would be of great importance, but would like to have some facts as realistic as possible, for example the duration of one day and one year for this scenario to be possible.