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Round and Round


Yesterday was the winter solstice, meaning the sun concluded its six-month southward course and seemed to “stand still” before beginning its journey north. Of course, this being a heliocentric neighborhood, the tilt, orbit, and rotation of Earth are what really move the sun through the sky. But don’t let that stop you from appreciating colorful crayon diagrams of the ancient “two-sphere” model of the heavens with Dr. Free-Ride on Adventure in Ethics and Science. If that’s not a useful enough approximation, you can get a modern understanding of solstices and seasonal dynamics from Anne Jefferson on Highly Allochthonous. Also on Highly Allochthonous, Chris Rowan reveals a snapshot of Saturn’s mysterious moon Titan, whose northern hemisphere is just emerging from a fifteen year winter. With middling gravity, apparent lakes and plenty of atmosphere, Titan presents a compelling prospect for extraterrestrial life, although it only receives a fraction of the sunlight we enjoy here on Earth. Finally, visit Ethan Siegel on Starts With A Bang! for a satellite view of the recent snowfall that blanketed the northeastern United States.

Links below the fold.