December 21 will the shortest day of 2017
The Winter solstice: The day — December 21 — marks the shortest day of the year 2017.
While the entire day is typically considered solstice, scientists can actually measure the precise moment it occurs. When the sun is directly over the line marking the Tropic of Capricorn — the latitude stretching across the southern hemisphere — solstice occurs.
What is Winter solstice?
Winter solstice is an astronomical phenomenon that happens when the Earth’s axial tilt reaches an optimum position, where the Northern Hemisphere is the farthest from the Sun. The Northern Hemisphere experiences the shortest day of the year on this day or the longest night as some might say.
The same phenomenon takes place on June 23 in the Southern Hemisphere.