On June 20, at 18 hours and 34 minutes the winter solstice occurs, which corresponds to the date in which the sun reaches its highest latitude on the Northern Hemisphere, which corresponds to the well-known Tropic of Cancer, located on the parallel 23°27’ north. The winter solstice marks the official first day of winter in the Southern Hemisphere; this is when the sunlight reaches obliquely this part of the planet, consequently, summer starts on the Northern Hemisphere.

The day of the winter solstice marks the day with the earliest sunset in the Southern Hemisphere, and the longest night. This is commonly known as the shortest day of the year.