The Summer Solstice is the first day of the Season of Summer. On June 21 the Sun is farthest north and the length of time between sunrise and sunset in the northern hemisphere is the longest of the year.

The Sun has been climbing in the sky and on this day it stops (solstice means "standing still sun"). The hours of sunlight have been getting longer and longer each day, but after today they will start getting shorter.

As the Earth circles around the Sun, it leans about 23° on its axis like a spinning top frozen in an off-kilter position. At this time, the entire Arctic area is continually exposed to sunlight even though the Earth is rotating.

Although the actual North Pole has had continuous sunlight for over three months by now, today everywhere above the Arctic Circle has 24 hours of sunlight.

Some cities in the far north, like Hammerfest in Norway, have many days of continuous sunlight.

This day is also the first day of the Season of Winter in the southern hemisphere, and there, the length of time between sunrise and sunset is the shortest of the year. While the Arctic has sunlight, Antarctica is in the dark.