What is the definition of a solstice, and when do they happen? Is the winter solstice always the first day of winter? Find out what causes these bi-annual astronomical events, as well as how they bring about the shortest and longest days of the year.
Transcript
Solstices are a planet’s longest and shortest days of the year.
The longest day often marks the beginning of summer and is called the summer solstice.
The shortest day often marks the beginning of winter and is thus called the winter solstice.
The Northern hemisphere’s summer solstice happens in June, when the North Pole is tilted most directly toward the sun.
This tilt means the summer solstice has the most hours of sunlight, and is the brightest day of the year.
The Northern hemisphere’s winter solstice happens in December, when the North Pole is tilted furthest away from the sun.
Because of this, the winter solstice has the fewest hours of sunlight and is the darkest day of the year.
In the Southern hemisphere, where the seasons are flipped, the situation is reversed.
The exact solstice dates may vary year to year on calendars, so meteorologists do not use them to mark the seasons.
That means the day of the winter solstice may not always correspond with the first day of winter.
Both the summer and winter solstices, along with the autumnal and vernal equinoxes, help shepherd in the changing of all four seasons.
