Monday, February 13, 2017

"Good Night, Moon"

Waning Gibbous

16.7 days old

95.7 percent lit

February 12, 2017
By Bob King

Stunning. Incredible. (click here) Alright, I'll shut up. But it's not easy when the photos are this inspiring. NASA's Cassini spacecraft has just returned some of the closest images of Saturn's rings ever taken. Photos that need to be shared widely.

The view at top shows the outer edge of the B ring, the brightest of Saturn's rings and easily visible in the smallest of telescopes. The edge appears sharp because the region next to the ring is cleared of ring particles by the moon Mimas. For every single orbit of Mimas, the ring particles — mostly made of water ice — are tugged on by the little moon. The repeated pulls force them into new orbits outside the gap. This all happens because the ring particles at this location orbit twice for every one orbit of Mimas. Astronomers call it a resonance, and it's much like finding the sweet spot when giving someone a push on a swing to provide the maximum boost....