Casey DreierDec 24, 2013

Cosmos with Cosmos Episode 9: The Lives of the Stars

Cosmos with Cosmos was a weekly series that encouraged Society members to re-watch Cosmos with a shared group, a cosmo(politan), or other drink of their choice. The Planetary Society published weekly episode discussion pieces to complement the original series before the Neil deGrasse Tyson-led 2nd season in 2014. You can currently watch the original Cosmos streaming on twitch.

Stars are born. They mature. They die. Their seeming impermanence is a facade; they age just like us. They have lives that come to an end.

But they also create. In episode nine of Cosmos, The Lives of the Stars, we revel in the other big idea of the series: we are all of us interconnected. Everything: biology (episode two), humanity (episode seven), and worlds (episode five) foreshadowed the ultimate fact that the matter that makes up all of us and everything we know (save for hydrogen and some helium) were created in the fiery bellies of massive stars. Their deaths created the building blocks of our life.

Of course, it wasn't always like this. The stars used to be thought permanent, immutable. They were as remote in distance as they were in essence. Our ancient (human) ancestors may have thought the stars powerful beings in the sky. Later, others believed they were the light of heaven shining through holes in the dark cloak of night. People thought they were made of far different stuff than everyday matter on Earth. Aristotelian belief codified the stars as distinctly different, made of stuff later called quintessence (the fifth essence, as opposed to water, air, fire, and earth).

As science progressed, and as we saw in episode seven, humanity learned the true nature of the stars: that they were made out of matter like that found on Earth, but impossibly far away. Even as our understanding grew and the stars joined our pantheon of physical objects, they moved beyond our grasp.

But we are closer to the stars than we ever dreamt. We come from the stars. So do the plants. And the rocks. And the Earth. We are star stuff, reconstituted atoms forged in stars long gone. We share not just a common ancestor, but a common progenitor with every thing around us.

This is Sagan's ultimate answer to the why of astronomy: we are connected to the cosmos. The study of the cosmos is ultimately the study of ourselves. Those lights in the sky, so distant and so mysterious, not only are made of the same stuff as us, but created the stuff of us. It's a beautiful, unifying idea.

The episode itself begins very strong, with a delightful, self-mocking sequence tracing the origin of an apple pie. I found myself wanting Strauss' weighty "Also Sprach Zarathustra," famously used in "2001: A Space Odyssey," as the musical accompaniment. As the pie is served to Sagan, he speaks one of the truly great lines from Cosmos: "If you want to create an apple pie from scratch, you must first invent the universe." What a weird, wonderful line.

We progress to a quick review of atomic theory and exponential numbers, and I was again struck by how simple Cosmos is in its presentation. We have a nearly eight-minute segment of just Sagan speaking to the camera. There are no fancy visualizations, just Sagan with a slice of pie and a piece of paper explaining the concept of atoms. It takes an unusual amount of charisma and force of delivery to maintain the audience's focus for so long. The new Cosmos series, borne of an era rich in cheap computer graphics, probably won't go this route.

After a chemistry lesson and a review of the elements (notably absent: the periodic table) we track the lives of stars that created the 92 mixtures of protons and neutrons presented to us. We revisit the Orion Nebula, but then bring it home to us, tracking the life of our own star, our Sun, and the sad, inevitable destruction of Earth.

Supernovas are mentioned, but I wish that they were given more time in this episode. Elements beyond iron are generated within the massive amount of energy released in the supernova process itself, and supernovae are just plain awesome, in the very literal sense of that word. Type 1a supernovae (when a white dwarf accretes additional matter) are also used to measure absolute distances in astronomy, though I can't fault Cosmos for not mentioning this, as the technique wasn't developed until the 1990s. There are also some very impressive computer simulations that try to reproduce the behavior of supernovae, though the process is notoriously time intensive. These types of supernovae also led to the discovery of the accelerating universe, a topic that will surely be discussed in the new series. The deaths of stars serve not only to sow their matter throughout the cosmos, but also to light our way.

M1, the Crab Nebula, by the Very Large Telescope
M1, the Crab Nebula, by the Very Large Telescope The Crab Nebula, a supernova remnant, was imaged in 1999 by the Very Large Telescope. The resulting picture uses mapped color from three filters.Image: European Southern Observatory

While the final lines of episode are poetic and very pretty, the discussion of globular clusters in high polar regions to the Milky Way seem shoehorned in. Maybe ending with a dying star was too depressing. I just couldn't see the connection beyond the fact that "we're talking about stars" -> "globular clusters have lots of stars" -> "globular clusters orbit the Milky Way in a cloud" -> "it would be cool to see the Milky Way galaxy rise from a star in a globular cluster." Would you ever get sunsets in a cluster like that, though? Wouldn't all the other stars in the cluster wash out the relatively dim light of the galaxy? I think back to Asimov's Nightfall here, and assume that everyone on that alien beach would go mad from the number of stars shining in the night sky on the once-in-an-eon total sunset.

The ending aside, this stands as one of Cosmos' strongest episodes. Along with the great The Backbone of Night, which explored the other big idea that the universe is ordered and knowable, The Lives of the Stars presents to us our deepest connection to this knowable cosmos. That all matter shares a common source, that the stars themselves are made of and make constituents of the physical world we experience today, is the ultimate repudiation of Aristotle. The mutable, ugly, imperfect Earth is not only made from the same material as the heavens, it is itself created by them.


  • "The evolution of life on earth is driven in part through mutations by the deaths of distant stars. We are, in a very deep sense, tied to the cosmos."

  • "Matter is composed chiefly of nothing"

  • "When we consider cutting this apple pie, but down beyond a single atom, we confront the infinity of the very small. And when we look up at the night sky, we confront an infinity of the very large. These infinities are among the most awesome of human ideas."

Science Update

  • We've confirmed that massive black holes are, in fact, at the center of many galaxies.
  • There is something in the universe that is not matter, something that seems like on the surface very similar to quintessence and about as well understood: dark matter and dark energy.
  • I mentioned above that a lot of our understanding about the acceleration, age, makeup, and expansion of the universe has occurred due to our increased understanding of supernovae.

Stray Observations

  • The first sequence of this episode reminds me how simple this show was. Sagan talks us through the concept of atoms and large numbers without the aide of any graphics, computer or otherwise.
  • Why is that pie so crumbly?
  • If only we knew how often we'd be hearing the word "Googol" in the future. They will need a very different explanation now to disentangle it from our favorite seek-verb."
  • This episode is a rich source of quotes for the great music video/mashup "A Glorious Dawn." If you haven't seen it yet, fix that:

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