The Moon of Nysegard

In the Apostle’s of Doom, when Hilda and some Nysegardians talk about the moon and moons of their respective worlds, I’m pretty sure they confuse a new moon with an eclipse. Rassnon claims that,”A new moon is when Atun, Nysegard and Tarth are all aligned at the same lattitude and the shadow of Nysegard covers Tarth and it is invisible in the night sky.”
This is an eclipse. Which would only occur during a full moon. A new moon occurs when the moon, Tarth, is between Atun and Nysegard, not the other way around.