Four and a half billion years ago, it is thought that a dying star exploded in one of the most energetic events to occur in our universe: a supernova.
This supernova would have sent a shock wave through the surrounding environment, causing a gas cloud to collapse and eventually form our solar system—the Sun at its center, circled by small rocks that coalesced with gas to become planets.
But not all of the rocks created in that celestial boom went into making planets. Leftover debris formed asteroids and comets that still shoot through our solar system, mostly unchanged over billions of years, explains astrophysicist and Santa Clara lecturer Kristin Kulas, a former NASA postdoctoral fellow who studies how galaxies form and evolve.
Imprinted in the ripples of their surfaces is our cosmic history. So in seeing the bright burst tailing the comet NEOWISE that sparked through the night sky this summer—not to loop back through our neck of the woods for another 7,000 years—we were witnessing the story of us, of how we came to be.
Though it hurtled by Earth at a time of profound loss and separation for our global community, when humans are feeling isolated and disconnected from the rest of the world, Kulas says there’s much comfort to take in NEOWISE. “As the comet continues on its long journey around the Sun, it reminds us to look up together,” she says, “and remember that all of humankind is connected on this small rock that orbits near the edge of our galaxy.”