The Earth is always facing the Sun in some way, because it's constantly rotating on its axis and orbiting the Sun. However, there are times when a particular hemisphere of the Earth is not facing the Sun directly:

* Night: When a particular location on Earth is not facing the Sun, it experiences night. This happens because the Earth is rotating, and only one side can face the Sun at a time.

* Winter Solstice: In the Northern Hemisphere, the winter solstice marks the day when the North Pole is tilted furthest away from the Sun. This means the Northern Hemisphere receives less direct sunlight and experiences shorter days. The opposite happens in the Southern Hemisphere, where it's summer solstice.

So, while the Earth never truly "not faces" the sun, we can use terms like night or winter solstice to describe periods when a specific hemisphere is not directly facing the Sun.