The Placidus system doesn't work north of the Arctic circle and south of the Antarctic circle. I am sure folks have been born north of the Arctic circle and heard of one child born in the Antarctic. Is equal house system used for that?

Greetings:

One of the primary reasons that house systems break down above arctic circle is because of the range of view. The higher (and Lower) you climb in latitude, the farther you can see around the curve of the earth. combine this with the 23 1/2 degree tilt of the earth's axis and you get some distinct problems defining the cusps for houses. In the Summer the Sun never sets, therefore, how do you distingish an ascendant? In the winter it never rises. Again, how do you set a risning sign? There is another consideration. The best models I have seen for a mechanical explination for how the houses work say that the Houses are tied to the Earths magnetic field. At about the point of the Arctic Circle is where the lines of force of the Earth's magnetic field begins to curve in on itself.
Having said all that, I think some kind of consideration needs to be made for how to distingish some type of houses for charts done at high and low latitudes. However, I know of no systematic research that has been done on how to establish one.

Ben