The Sun rises over Stonehenge, as people take part in a winter solstice ceremony at the ancient ... [+]
It’s all about the tilt. Depending on where you are in the world, the solstice occurs this weekend late on Saturday, December 21, 2019 (in North America) and Sunday, December 22, 2019 (in Europe, Africa, Asia and Australasia).
In the northern hemisphere it means the shortest day of the year, the longest night, and up in the Arctic Circle, it’s a time when the Sun never rises. In Antarctica, the midnight Sun shines all day as the southern hemisphere sees its longest days and shortest nights.
A December solstice from space. The change of the season, which relates to the position of sunlight ... [+]
What’s the science behind the solstice?
It happens because we live on a planet with an axis tilted by 23.5º relative to our orbital plane—the plane of Earth’s orbit around the Sun. That tilt affects how much sunlight each hemisphere of Earth gets at different times of the year, both in terms of how long the days are how low or high it hangs in the sky. It’s about a change in the orientation and angles between the Earth and the Sun.
That tilt—Earth’s “obliquity”—gives us the seasons, and this weekend marks the beginning of winter in the northern hemisphere (where the days are at their shortest, nights are longest, and the Sun hangs at its lowest in the daytime sky) and summer in the southern hemisphere (where the complete opposite happens).
Look at a map of Earth’s orbit around the Sun and you can see what’s happening.
Seasons Change Because More Direct Sunlight Falls On Some Parts Of Earth Than Others At Different ... [+]
What day is the solstice?
That depends on where you are. Solstice is a global moment marking the moment when the Earth's axis is at its maximum tilt away from the Sun, when the Sun it hangs above the Tropic of Capricorn at midday in the southern hemisphere. Consequently it can happen at night in other parts of the world. This weekend’s solstice will occur globally at 4:19 a.m. Universal Time on Sunday, December 22, 2019, though in North America that’s 11:19 p.m. EST on Saturday, December 21, 2019.
Does the solstice mark the start or middle of winter?
That depends on who you ask. Astronomical winter in the northern hemisphere officially starts on the date of the winter solstice each year, though others call it midwinter. Astronomical winter begins on 22 December 2019 and ends on 20 March 2020. However, meteorological winter begins on December 1 and ends on the last day of February.
The Tropic of Capricorn in Namibia.
What are the Tropics of Capricorn and Cancer?
These are lines of latitude running parallel with the equator that mark where the Sun “turns.” At midday on December’s solstice the Sun appears to be directly above the Tropic of Capricorn—the Southern Tropic—an imaginary line around the Earth that’s 23.5º below the equator. It runs through South America, southern Africa and Australia. At midday on June’s solstice, the Sun appears to be above the Tropic of Cancer—the Northern Tropic—an imaginary line around the Earth that’s 23.5º above the equator. It runs through Mexico, northern Africa, south Asia and China.
The Tropic of Capricorn on an early globe.
Wishing you clear skies and wide eyes.
#News | https://sciencespies.com/news/can-you-explain-this-weekends-winter-solstice-get-to-know-the-simple-science-behind-the-seasons/
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