What does the term “solstice” imply? When do solstices occur? In this article, we’ll tell you everything you need to know about solstices.
What happens on a solstice day?
Solstices occur because the Earth’s axis is tilted at 23.5 degrees. Two times a year, one of the Earth’s hemispheres reaches its maximum inclination toward the Sun. As a result, this hemisphere gets the most sunlight and experiences the longest day in a year — this event is called the summer solstice. At the same time, the other hemisphere gets the least amount of sunlight and experiences the shortest day — this event is called the winter solstice. In astronomy, the two solstices mark the transition from spring to summer and from fall to winter.
For an observer located at mid-latitudes, on the summer solstice, the Sun will be positioned at its highest point in the sky. In contrast, during the winter solstice, the Sun will be at its lowest point in the sky.
What are the dates of each solstice?
As we’ve already mentioned, solstices occur twice a year — around June 21 and December 21. The June solstice can occur between June 20 and 22, while the December solstice can happen between December 20 and 23. Depending on the season, a solstice is called either the summer one or the winter one. Remember that solstices — as well as the seasons — are reversed in the Southern Hemisphere compared to the Northern Hemisphere.
When is the summer solstice in 2021?
In the Northern Hemisphere, the first day of astronomical summer is marked by the June solstice. In 2021, it happened on June 21, at 03:32 GMT (June 20, 11:32 p.m. EST). In the Southern Hemisphere, summer starts on the December solstice, which will occur on December 21, at 15:59 GMT (11:59 EST) this year.
When is the winter solstice in 2021?
In the Northern Hemisphere, the first day of astronomical winter is marked by the December solstice. In 2021, it will occur on December 21, at 15:59 GMT (11:59 EST). South of the equator, winter starts on the June solstice, which occurred on June 21, at 03:32 GMT (June 20, 11:32 p.m. EST) this year.
When is the longest day of the year?
The day with the most sunlight hours in a year happens at the summer solstice. In the Northern Hemisphere, it takes place around June 21, and in the Southern Hemisphere — around December 21.
When is the shortest day of the year?
The day with the fewest daylight hours in a year happens at the winter solstice. In the Northern Hemisphere, it takes place around December 21, and in the Southern Hemisphere — around June 21.
What is the difference between a solstice and an equinox?
To put it briefly, solstices are the longest and shortest days of the year, while equinoxes are dates when day and night are equally long. You can learn more about equinoxes from our article on this topic.
Did you know?
- North of the Arctic Circle, the Sun is visible for 24 hours around the June solstice; inside the Antarctic Circle, the same phenomenon happens around the December solstice.
- Scientists believe that Stonehenge was specifically designed to line up with solstices. If you stand at the center of Stonehenge on the summer solstice, you’ll see the Sun rising exactly behind the monument’s Heel Stone.
- On the June solstice, the Sun is positioned directly above the Tropic of Cancer. It is the northernmost latitude where the Sun can be seen directly overhead. The tropic got its name thousands of years ago when the Sun was in the constellation Cancer at the June solstice. Today, the Sun has moved to Taurus due to the Earth’s axial precession, but the old name remains.
Thanks for reading this article! If you have questions about solstices, please feel free to ask them on our social media. If you want to expand your astronomical knowledge, take our quiz on equinoxes and solstices!