It was a little over four and a half billion years ago, in an undisclosed location perhaps a few thousand light years nearer to the center of the Milky Way galaxy than where we find ourselves today.
Great billowing clouds of molecular gas and dust — the supernova remnants of a mega-massive star gone kablooey — swirled and danced in space. This fog was mostly hydrogen and helium; perhaps 2% of the material consisted of heavier elements, a fine dust of iron and carbon and the rest, which had been synthesized through fusion in the exploded star’s core. Metals, in astronomy terms.
A supernova is a messy affair — the distribution was not perfectly even. There were clumps in the vapor. Through the action of gravity, these pockets of density attracted yet more density, more material, into themselves. An object began to form, almost a solid thing. There was angular momentum, rotation; the little upstart anomaly spun and heated as it contracted under its own weight.
Most of the mass gathered into a sphere at the center, where the pressure of so much stuff in such a small space eventually grew great enough to ignite fusion.
Out of the old star, a new generation of star was formed. Meanwhile, the rapid rotation flattened the matter around our protostar into a disc — a protoplanetary disc, so rich and thick with dust that the central furnace was obscured.
These pictures are from Hubble Space Telescope observations of the Orion Nebula, but they are a fairly good approximation of what the birth of our solar system would have looked like. There, against the light background in the center of the second image, is a dark speck, a mere mote, almost completely hiding the infant star burning and churning within.
That is how our Sun and its retinue of planets and asteroids and comets began their existence.
As often as not, these protoplanetary discs host more than one star. Jupiter may have tried and failed to ignite, ultimately acquiescing to a life of tending the planetary herd, leaving the Sun to shine uncontested. Its demotion greatly increased the stability and potential complexity of our system.
Given the chemical signatures we see, it is very likely that our environment coalesced in this way alongside hundreds to thousands of others — a large cluster of star systems formed from the remains of some titanic stellar predecessor.
The Sun and its sibling stars, identities unknown (though there have been suspects), have long since migrated out and away from that primordial stellar tomb turned nursery. We are cosmic orphans; we don’t know who our parent was, or where “the old homeplace” really is. We probably never will.
Our planet’s composition, its geology and tectonics, its atmosphere and biosphere, are all enabled by just a small fraction of the 2% of dust found amid all that etheral gas: life, death, vegetation, the seven seas, grandma’s lasagne, the device in your hand or on your desk right now. All of it began in a clump that first grew, then contracted, spun, ignited, and flattened, against all odds.
Try not to roll your eyes when someone points out that we’re all made of stars. It’s essentially correct.
