logical deduction - rescue operation - where is your partner?

Your partner's space ship has crashed on an uninhabited planet. Only the radio transmitter and his compass were still in operation. He asks you to rescue him, and tells you how to find him by the following story.

1. He went one unit to the south


2. Then he went one unit to the west


3. Then he went one unit to the north


4. After that journey, he was back at the beginning where he started

Where is your friend? Can you really find him?

Answer

I believe the complete answer is the following:

• He could be at the north pole


• He could be near the south pole, exactly one unit north of a place where the parallel is one unit long.


• He could be one unit north of a place where the parallel is $1/2$ unit long.


• and so on wih $1/3$, $1/4$,...

The point being when he goes west, he could be that he's making a total round (or several), before going north back to his original place.