Recent discoveries show that our solar system lies in the middle of a giant “bubble” in space, which encompasses a volume five hundred light-years wide around us. As a result of this, there are relatively few star systems inside that region, and at its edge, a frenzy of star formation has taken place.
The Local Bubble, as it’s become known, started to form approximately fourteen million years ago, when as many as fifteen supernova explosions blasted out the region. While these bubbles have been seen before in other parts of space, it’s only recently been discovered that we are in one.
Our solar system wasn’t in the bubble when it formed. It drifted into the region around five million years ago and should leave the bubble in about another eight million years. A relatively short time by astronomical standards, but something about the timing caught my attention.
Around the time we drifted into the Local Bubble, life on Earth was limited to very simple forms such as single-celled bacteria, algae, and other microbes, and existed in the oceans surrounding the single supercontinent of Rodinia. Then something strange happened. Something now called the Cambrian Explosion.
In just over ten million years, an eyeblink in Earth’s history, dozens of new life-forms emerged from the oceans. Ninety percent of the life we know today can be traced back to that one event. It’s safe to say that, effectively, complex life began at that time.
So I wonder, was this all a coincidence? Or was there something in the supernova remnants that triggered these changes when we entered the bubble? Do we owe our very existence to the supernovas that created the bubble?
Carl Sagan talked about how the more complex elements in the universe were formed in supernovas and said poetically that, “The cosmos is within us. We are made of star-stuff.” Perhaps the link is even more intimate than he imagined!