I have this clock app that shows where sunlight is falling on a Mercator projection

[capri0mni]

This is what it looked like at the September Equinox, at 4:19 Eastern Daylight Time:

[Image description: A Mercator projection map showing the land in grey and the oceans in white, minus Antarctica. Overlaid on this is a sine curve like silhouette that shows where light and shadow is falling on the Earth at that moment. The sides of this are almost perfectly vertical, showing equal daylight for all points on the map, no matter how far from the equator they are. Description ends]

This is what it looked like, yesterday, during the December Solstice, at 3:19 Eastern Standard Time (officially, the "same" minute):

[Image description: the same map, but this time, the sine curve indicating sunlight is steeply angled, being narrower in the Northern Hemisphere and wider in the Southern Hemisphere, showing the land in the arctic circle in complete shadow, and where the land in Antarctica would be in complete sunlight. Description ends.]

So now you know: the "Reason for the Season" is the Earth's axial tilt!

Glad Yule or Litha! Depending on which side of the equator you reside...

Comments

[sonia]

Thanks for the cool images! What clock app is that?

Also, glad Yule!

[capri0mni]

The name in the header bar is simply "Alarms & Clock" I found it as a free download in the Microsoft Store (It also has an alarm feature, a timer, and a stopwatch)

Glad Yule!

[sonia]

Thanks! I have an iphone, but I did find this similar app. So many cool toys out there!

https://itunes.apple.com/us/app/day-night-map/id741375889

[capri0mni]

That is cool!

I also found this online version:

https://www.timeanddate.com/worldclock/sunearth.html?month=12&day=22&year=2018

[sonia]

Ooooh, thanks!