“The cosmos is within us. We are made of star-stuff.”
4.6 billion years ago, a massive cloud of gas and dust was swirling in the vast expanse of space. It was nebulous, in both the literal and figurative senses: amorphous, still taking shaping, edging on the precipice of potential. And it was being crushed under its own weight—until this nebula finally collapsed under its own gravity, causing it to swirl faster and faster until it spun out into a flattened disk. As it did so, the majority of its mass (99.8%) was pulled toward its center, where it heated into a core and something bright, hot, and new was born: a star.
That particular star was the Sun, the very same one that may be shining or setting outside your window wherever on Earth you are reading these words. As for the rest of the matter that made up the solar nebula—that tiny figure, less than half of a percentage—some of it was whisked away on the star’s solar winds. The remainder scattered into the Sun’s newly-formed orbit, eventually arranging into rocks and planets, plants and animals, people and all our plights.
Despite how our lives revolve around it, the Sun is an average star (size-wise). It sustains itself the way all stars do, through the nuclear fusion of hydrogen atoms which create other elements in their cores. The energy from these reactions keeps the star from collapsing in on itself. After a star fuses all of its hydrogen, its core starts to collapse and become even hotter; expanding outward, average stars become red giants. Over time, they eject their outermost layers until their cores are exposed, becoming white dwarfs that will cool and fade away into the night sky.
Massive stars—those that are five times the mass of the Sun— meet a different fate. As their hotter cores collapse, nuclear reactions will produce iron, using so much energy that the star has nothing left to protect itself from collapsing completely. In the blink of an eye, it shrinks from 5,000 to 12 miles wide. Temperatures hit over 100 billion degrees as the core explodes, releasing a dazzling burst of energy and light: what’s known as a supernova. The iron and other elements are scattered across the galaxy to reform in new combinations: new nebulas, new stars, new life.
And so stars are the building blocks of the universe. They create and disseminate the heavier elements that allow for life as we know it: carbon, nitrogen, oxygen, iron, and so on. You have likely heard that you are stardust, and it’s true. The iron in your blood, the oxygen in your lungs, the carbon that is found in all life on Earth—these elements only came to be during the life and death of these celestial phenomena, these forces that hang suspended in the sky.
Humanity has always searched the stars for answers, whether through navigation, prophecy, or clues to our wider universe. They are the lights we look up to find our way, stories we have drawn in the lines between them. What we are seeing is ourselves, our makers. When I feel overwhelmed by my own daily dramas, when I am on the verge of collapsing under their gravity, I remind myself of this: that I am here because of exploding supernovas. That I can be light, when I need to, and that I can also be iron. That I am still shaping, still expanding. That someday I too will burn out and become part of everything else, but burn so brightly before I do.
The image at the start of this newsletter was taken by NASA’s James Webb telescope, of a star being formed: the disk suspended there in the center. When I look at it, I see time and an hourglass. I see endlessness, the infinite cosmic recycling system of unimaginable proportions that binds this universe. I see all of it—everything ancient and new, matter scattered across the void, across nothing into something, something spectacular. Something like you and me.