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Cosmos with Cosmos Episode 9: The Lives of the Stars

In which we are star stuff

Posted by Casey Dreier

24-12-2013 15:11 CST

Topics: product review, solar system formation, fun, astronomy, stars and galaxies

Cosmos with Cosmos is a weekly series that encourages people to get together and watch Cosmos with a cosmo(politan) or drink of your choice. We're posting weekly episode recaps and discussion through February of 2014. This series is made possible by members of the Planetary Society. If you like what you're reading, please consider joining the Society or donating $10 to help support projects like this in the future. To learn more about this series and find out how to watch Cosmos, see our introduction.

« Episode 8: Journeys
Through Space and Time

Episode 10: The Edge of Forever »

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

European Southern Observatory

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.

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:

« Episode 8: Journeys
Through Space and Time

Episode 10: The Edge of Forever »

See other posts from December 2013


Or read more blog entries about: product review, solar system formation, fun, astronomy, stars and galaxies


Jimi Maze: 12/24/2013 06:56 CST

Interesting that Carl took so much care to destroy Astrology in an earlier episode and now he builds a case that we are fully interconnected with the stars, based on a lot of hypothesis. It does make sense, yes. Twice now they have used Pink Floyd music uncredited. I'm not a PhD but I find a lot of his 'facts' to need salt to swallow. I guess I need to read more into the scientific data that supports such claims. I found it interesting to learn that helium was once thought of as a theoretical gas found only on stars. How did they make elf voices in the past? It bothers me when science edutainers talk about super condensed matter. Carl described bouncing a ball of White Dwarf through the Earth, but you have to skip so many laws of gravity and proximity to make this happen, why bother? Silly! Thanks Casey. Merry Solstice Holidays

Adolf Schaller: 12/25/2013 01:05 CST

@Jimi Maze: much of what you find problematic pertains to an exposition back during production in 1978-79. As for your sweeping take of "edutainers", we might fret considerably over the lack of anything remotely better in this day and age a third of a century along than what is emerging as what may have been a peak in the popularization of science. You may be too young to appreciate that and ill-informed over how hard it is to work against the existing current of popular appeal in order to supply content worthy of your and our standards. When I worked on this program it was all about actually doing, not about complaining. As for the Pink Floyd music: are you watching the original or a later version of the series?

Torbj??rn Larsson: 12/29/2013 07:26 CST

Think of the possible killer solar surface sequences of the new show! That exciting sequence aside, I found the discussion about wormholes more mystifying than the mentioning of time machines in an earlier episode. It's on par with the globular cluster shoehorn. But today wormholes are popular again, since Maldacena's holography tool shows that they are yet another connection between quantum and gravitational physics - wormholes appears when entangled particles are separated by acceleration that causally disconnects them (by having one particle pass through an event horizon say). Only now wormholes are mediating correlations, the idea that particles can pass is gone. Some astrobiology: - Despite Sagan being a greenhouse warming specialist, he puts the heat death of our biosphere to ~ 5 billion years at the inception of our sun's red giant stage. Today's estimates are ~ 1 billion year for plants &animals, ~ 2 billion years for prokaryotes. - They were optimistic about the "billions and billions" of planets by finding a lot of protoplanetary disks. Rightly so, as we now have passed 1000 confirmed exoplanets and estimate them at 100's of billions in our galaxy alone.

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