The center of the Sun crossed the Equator moving south on September 22 (the Autumn Equinox), and viewed from the North Pole, one half of it was below the horizon. The top half was still peeking above the horizon and it still provided continuous sunlight.

On September 24 at the North Pole, the Sun fully sets as its trailing edge disappears below the horizon. The Pole enters a period of twilight, and there will be no more sunlight for another 176 days!

Twilight is light from the sky when the Sun is just below the horizon - think of twilight as having enough light to not have to turn your lights on - such as we see just before the Sun comes up in the morning and just after it sets in the evening.

However, directly at the Pole, this period of twilight lasts for about 12 days - until the Sun has moved so far south that darkness fully sets in.