ASTROPHYSICS: Saturnian day deduced from ring formations

摘要

Data from NASA’s Cassini spacecraft has enabled a more accurate estimate of the length of a day on Saturn.The new estimate of 10 hours,33 minutes and 38 seconds,is based on imagery of the formation of the Saturn’s rings,which respond to vibrations in the planet’s interior.Using this imagery,Christopher Mankovich,an astronomy student at UC Santa Cruz,developed models of Saturn’s internal structure to match the wave patterns.These then allowed him to track movements of the planet’s interior,including its rotation.”Particles throughout the rings can’t help but feel these oscillations in the gravity field,”Mankovich said.”At specific locations in the rings these oscillations catch ring particles at just the right time in their orbits to gradually build up energy,and that energy gets carried away as an observable wave.”