In design terms, I would claim that Sunset Calculator is a "component" (an integration of units), with a "required interface" (i.e. abstracted) that provides th

In design terms, I would claim that Sunset Calculator is a "component" (an integration of units), with a "required interface" (i.e. abstracted) that provides the coordinates. A role of one unit inside this component is to use the provided coordinates and only perform the calculation.