Photo Of The Day
October 11th, 2007at 07:21pm Posted by Eli
NASA/JPL/Space Science Institute
Poor Iapetus, the bane of the Saturn moons, with a half-black, half-white countenance that speaks of a mysterious past.
The two-toned world has baffled astronomers since its discovery more than 335 years ago, but a recent inspection by the Saturn-orbiting Cassini spacecraft may have cracked the case.
Scientists believe that as the moon orbits around Saturn, it rams into dusty particles left behind by sister moons or other objects, creating a dark mask across its leading hemisphere.
The dark side reflects less sunlight than the bright white surfaces trailing behind. The extra heat melts surface ice and even releases water vapor, which then condenses on the nearest cold spot. That could be on the moon’s poles, or somewhere along the sheltered back side, where it refreezes and recoats the moon’s already bright, highly reflective surfaces.
Losing the lighter-toned water ice leaves Iapetus’ dark side even darker, creating a yin-yang world where there is no grey.
Awesome. It’s even more beautiful if you’re a Republican.
