And We’ll Get Back There Again

For all you non-chemists in the crowd, did you know that life on Earth began with a sort of “starter yeast” of carbon-bearing compounds and other species of molecules that came from space? It’s true.

Naturally occurring ones Interstellar chemical labs contributed the iron that flows in our blood, the calcium that makes up our bones and the carbon-based molecules that make US up. And all that stuff came from stars that lived and died long ago. In the dying, they contributed elements built up over eons of time in stellar cores and atmospheres. Eventually those elements found their way to Earth, and into other chemical stewpots.

In a sense we are really the ashes of old stars, brought to life through massive and eons-long chemistry experiments. We began in stars like the ones that died to produce the Helix Nebula (left, a planetary nebula formed when a star like the Sun died) or the progenitor star that created the Crab Nebula (right) blew up more than 7,000 years ago. Near these two objects, clouds of gas and dust are scattering the chemical precursors of life. Someday perhaps they’ll combine to create new life forms.

Some 5 billion years from NOW, our Sun will start to expand and engulf the inner planets. That means that Earth (and by extension) all life upon it, will be vaporized; in essence, returned to the gas and dust from which we came. All that we were, plus all that the Sun will exhale in its dying days, will rush out to space to provide fodder for yet MORE new life, should there be places where it can form. So, while I’m not a religious person, I do find it interesting that in an astronomical sense, we are truly ashes to ashes, and dust to dust. We’ve come from space and we’ll be headed back, one way or another.