Many amino acids, sugars and other molecular building blocks of life are chiral, meaning they have left-handed and right-handed versions. Like your hands, these are mirror opposite pairs that cannot be superimposed on each other. There's really no reason for one to prevail over the other, but this symmetry breaking happens anyway; life on Earth is largely left-handed (though a recent study suggests its lower forms can be ambidextrous). In 2009, NASA researchers studied meteorites and found that left-handedness also seems to prevail throughout the cosmos. Last week, they said this quality can be found in an even wider range of space rocks than they thought.