Blue skies and ice on Pluto

 

This dwarf planet on the edge of our solar system keeps offering surprises almost on a daily basis.  NASA reported today that the New Horizons spacecraft has found numerous, small exposed regions of water ice on the surface of Pluto.  Data collected from the Ralph spectral composition mapper, an imager to map surface compositions and temperatures, made the discovery, but only in certain areas.  Exposed ice does not appear in larger expanses, which could mean it is covered or masked by more volatile ices.

Other images sent from New Horizons show blue atmospheric hazes.  Although the particles causing the hazes are probably gray or red, they scatter blue light that indicates the size and composition of the particles.  Scientists theorize tholins in the atmosphere are the cause.

The term ‘tholin’ was coined by Carl Sagan and Bishun Khare in 1979.  In their laboratory, they produced complex organic solids from “cosmically abundant” gases, such as methane, ethane, ammonia and water.  Sagan and Khare say these particles are relevant to the origin of life.

This process was observed in the upper atmosphere of Titan, Saturn’s moon, where UV light ionizes nitrogen and methane molecules.  They react with each other to form more and more complex ions.  This ionizing and recombining results in large molecules that become small particles.  Volatile gases condense on their surfaces and coat them with ice frost before they fall to the planet’s surface, giving Pluto a red color.