In the first episode of his famous TV series about space, “Cosmos: A Personal Voyage,” the late astronomer Carl Sagan wastes no time dramatically setting the stage.
“The surface of the Earth is the shore of the cosmic ocean,” Sagan says. “Some part of our being knows this is where we came from. We long to return, and we can, because the cosmos is also within us. We’re made of star stuff. We are a way for the cosmos to know itself.”
Building on that spirit, Jennifer A. Johnson, an astronomer at the Ohio State University, has hacked the periodic table of elements to show exactly what kind of “star stuff” Sagan is talking about, and how much.
Her graphic below, which we first saw in a tweet by science writer Corey Powell, shows the violent cosmic origins of every element in the solar system — including all of the atoms in our bodies:
Johnson said the idea for plotting out the origins of periodic elements started at a meeting 8 years ago with fellow astronomer Inese Ivans, but that early attempts (like this one) were unsatisfying.
“Once you have spent ~20 years getting […] this info into your brain, the main difficulty is not wanting to make the plot too complicated to include every little detail,” Johnson told Business Insider in an email. “In several cases I needed to say ‘OK, that’s close enough to get the point across’.”
She ultimately colour-coded six types of cosmic events that can forge new atoms: the Big Bang, cosmic rays, merging neutron stars, and three different classes of exploding stars. Each portion of colour shows the relative amount of element the event made.
It shows that many critical elements in our bodies — oxygen (O), phosphorus (P), and sulphur (S) — came out of giant exploding stars called supernova, while others — like carbon (C) and nitrogen (N) — came from dying, sun-like stars. Hydrogen (H), meanwhile, which is a key component of water, came out of the Big Bang.
Johnson said all the scientific evidence behind the chart is not her doing and “goes back decades,” yet is still evolving.
“You have stars with the mass of the Sun dying, you have massive stars and white dwarfs blowing up, you have neutron stars […] then swirling into each other and merging,” she said. “It’s hard work!”
The elements technetium (Tc) and promethium (Pm) are grey, Johnson says, “because the only time we see them is when we make them in colliders or nuclear bombs.”
Johnson said one thing her chart doesn’t show is how long it took to get each element. To get all the core elements of life in the right abundances, for example, plus rock-building elements — magnesium (Mg), silicon (Si), and iron (Fe) — it took billions upon billions of years.
“So right after the Big Bang — no planets, no life until stars had time to enrich the Universe,” she said. “‘So ‘long ago, in a galaxy far, far, away’ can’t have been too long ago!”
If the contrast isn’t shining through very well, Johnson also made a colorblind-friendly version of the chart.