The chemical elements, carbon (C), hydrogen (H), nitrogen (N), and oxygen (O) are the elements that comprise the cells of living organisms. These elements form basic molecules required to sustain life. Surprisingly, these basic elements can actually be found commonly throughout the cosmos. The real challenge is in the very strict conditions that must be met in order for these elements to combine in such a way that life be formed and sustained. This is why despite the abundance of these elements throughout the cosmos, the quest for extraterrestrial life is very difficult.
