For most of here on planet Earth, sunrise, sunset, and cycle of day and night (aka. the diurnal cycle) is just a simple fact of life. As a result of seasonal changes that happen with every passing year, the length of day and night can vary — and be either longer or shorter — by just a few hours. But in some regions of the world, this cycle is completely different. In these parts, located around the Earth’s poles, the Sun does not set during certain times of the year. And there are also seasonal periods where a single night can last many days. Naturally, this gives rise to certain questions. Namely, what causes the cycle of day and night, and why don’t all places on the planet experience the same patterns? As with many other seasonal experiences, the answer lies within the fact that the Earth rotates on its axis, and the fact that this axis is tilted. Earth’s rotation occurs from west to east, which is why the Sun always appears to be rising on the eastern horizon and set...