Imagine yourself in Gdansk, Poland, just south of the Arctic circle. It's summertime, it's midnight, and you can still see the twilight glow of the Sun. In what direction are you looking?
This question is easier than it may seem; the answer is hidden in the vocabulary.
If you were in the Arctic Circle during summertime, the sun would never set. This region of the world, due to the Earth's axial tilt, would be constantly pointed toward the sun, regardless of the rotation of the planet.
In Gdansk, we're just south of the Arctic Circle. This means that the sun does set, but just barely; when it does drop below the horizon, there isn't really a transition into "night", but more of a twilight.
Since night, or midnight at least, always occurs while the viewer is positioned between the Earth and the Sun, then the viewer must be on the "dark" side of the Earth, with the sun on the opposite side. Were the viewer to travel a little farther north they would enter the Arctic Circle and see the sun pop over the horizon. Therefore, if the viewer is in Gdansk at midnight and looking at the glow of the sun, they must be facing north.