"This December, like every December, will include a single moment - often marked by a particular day, which is December 21st here in 2025 - where our planet's axial tilt is perfectly aligned with the invisible line connecting the Earth to the Sun. In December, it's the northern hemisphere's pole that's tilted away from the Sun, while the southern hemisphere's pole is tipped towards it; in June, the opposite situation is true."
"Although there are many factors at play that determine the behavior of each planet - its spin and orbital angular momenta, the eccentricity of its orbit, the effects of General Relativity and the other planets - there's only one that determines when the solstices are: axial tilt. As every planet revolves around the Sun, it rotates on its axis, and only the orientation of that axis matters."
"Solstice literally means "Sun stands still" in Latin. If you were to trace out the path of the Sun in the sky throughout the year, such as with a pinhole camera (as shown above), you'd find that the Sun follows a set of paths that all correspond to it rising somewhere in the east/northeast/southeast, reaching a maximum height overhead, and setting somewhere in the west/northwest/southwest."
Solstice occurs when a planet's axial tilt aligns with the line to the Sun, producing maximum tilt of a hemisphere toward or away from solar rays. In December the northern pole tilts away while the southern pole tilts toward the Sun; in June the reverse holds. A hemisphere tipped toward the Sun experiences longest days and shortest nights; tipped away produces long nights and short days. Many factors influence planetary behavior, but only axial tilt sets solstice timing. Summer solstice occurs when a hemisphere is maximally tipped toward the Sun; winter solstice occurs when it is maximally tipped away. Solstice means 'Sun stands still.'
Read at Big Think
Unable to calculate read time
Collection
[
|
...
]