Drinkability: Medium.   As early as the 1600s, observers suspected that the white blotches that cover Mars’ poles and the wispy patches...


Drinkability: Highest.   There are two main theories as to how water first appeared on Earth.       The...
Supernova remnant Cassiopeia A. When stars of sufficient size die, they explode, blowing out the elements they have created, including hydrogen and oxygen. The constituents of water.

Photo courtesy of: NASA

The First Step

Drinkability: Lowest.   Water is composed from two hydrogen and one oxygen molecule (hence the chemical and colloquial name, H2O). Some of...