May 15, 2019
Cosmos Recap: 99 Problems But A Hypernova Ain't One
This week, Cosmos: A Spacetime Odyssey is determined to get cute with its episode title: “Sisters of the Sun” is about our sun’s stellar sisters — all the other types of stars out there — but the episode is also about the women at Harvard who, in the early decades of the 20th century, made key discoveries about those stars, what they’re made of, and how they’ll eventually die. Also, this week’s episode reprises a line of old-school Carl Sagan narration that has become something of a nerd touchstone — which we’ll get to later.
We start off with a brief review of the constellations, those star-patterns that humans have found mythic pictures in, though not the same pictures from culture to culture. An animated segment shows us the Kiowa and ancient Greek stories of the Pleiades, the star cluster that — aha! — has been depicted in legend as a group of maidens or sisters. In the Kiowa legend, women chased by angry bears are lifted to the sky by a friendly rock, and the bears’ claws on the sides of the rock formed the volcanic remnant that boring Europeans named “Devil’s Tower” — and somehow Neil deGrasse Tyson sits under the stars by that mountain without whistling the Close Encounters theme.
Probably a royalties thing.
After the commercial break, we zip off to Harvard in 1901 to meet astronomer Charles Pickering’s “computers” — the women who mapped and classified stars, largely because Pickering could hire a larger team with his limited budget. Does Phyllis Schlafly know about this benefit of gender wage gaps? (Anecdote from the wiki that could just as well have gone into the animated segment but did not: the first woman Pickering hired, Williamina Fleming, originally worked for Pickering as a domestic; she got her job because the astronomer was so irritated at his male assistants that he declared his maid could do a better job. And she did.) “Pickering’s harem” (such charming quaint terms!) included some pretty brilliant astronomers, like Annie Jump Cannon (voiced in the animation by Marlee Matlin), who developed the standard classification system for stars, and Henrietta Swan Leavitt, whose work made it possible to determine distances between stars and the size of the universe itself. “For some reason, you’ve probably never heard of either of them. I wonder why?” says Tyson, with exactly the right amount of disappointment in our country’s science education … and/or history of educating women.
Cannon, a Wellesley grad, used spectroscopy to classify different types of stars by their spectrums, which reveal what elements exist within the stars. She developed and refined the “Harvard classification scheme,” which classed stars into seven categories by letter — O, B, A, F, G, K, M — and then further broke each letter into ten gradations. (Does Tyson mention the sexist mnemonic — “Oh, Be A Fine Girl, Kiss Me” — associated with those classes? He does not, because he is An Gentleman. But he could have at least mentioned the astronomy student’s lament: “Oh Boy, Another F’s Gonna Kill Me”.)
After a commercial, we jump to another Harvard scholar, Cecilia Payne (voiced by Kirsten Dunst), who came to the school in 1923 and used Cannon’s spectral classifications to revolutionize our knowledge of the composition of the stars — most of the suckers are made of hydrogen and helium, an insight so radical that her dissertation was initially rejected by astronomer Henry Norris Russell. Happily, four years later, Russell realized he was A Idiot, gave her credit for the discovery, Payne’s book became the standard text, and all was right with the hydrogen- and helium-filled universe (see also a fun snarky discussion of the oversimplifications of that thumbnail narrative over at The Wire It’s GOOD). “The words of the powerful may prevail in other spheres of human experience,” Tyson intones, “But in science, the only thing that counts is the evidence and the logic of the argument itself.” And, OK, the office politics, the funding, and the institutional barriers that may still keep women from getting their due (yes, that Wire piece is definitely worth a read).
And now, on to the CGI star explosions, which are also a lot of fun. We start with a brief biography of stellar nurseries, with star clusters forming from gas and dust, like the “toddlers” of the Pleiades, to mature stars like our sun. Mostly it’s just a quick tour, and then we get to the ultimate destiny of stars — exhaustion of their gaseous fusion fuels, and eventual collapse. We get a short-form discussion of the eventual death of our sun, in a few billion years, and then a look at how other stars with different masses croak — especially nifty examples like Sirius, whose companion star is a white dwarf. And when a dying Sirius starts expanding into a red giant, its gases will be absorbed by the white dwarf, and boom — a lot of nuclear explosions, aka novas. Or perhaps you’d prefer Rigel, about 15 times as massive as the sun, which will eventually collapse in on itself, then explode as a supernova, then collapse further into a pulsar. Or the even more massive Alnilam in Orion’s belt, which is even denser, and after it goes supernova will become a black hole. It’s all awfully pretty, really.
And finally there’s the still more massive (and it’s hard, when writing about this stuff, to keep stretching out your superlatives) binary star system Eta Carinae, 100 times the mass of the Sun, which will explode as a hypernova, destroying any other “nearby” (within tens to hundreds of light years) star systems, but from which we’re sufficiently distant — about 7500 light years — that it will merely shine in the Southern Hemisphere like a second moon. Also, it may have already happened, and we’re just waiting for the light to reach us. Again, time to crank up the digital effects. Ooooh, ahhhhh.
The episode closes with Tyson reminding us that we and everything in our physical world are made of recycled star stuff, the elements ejected by exploding stars hundreds of millions of years ago. It gets a little poetic, really and that’s fine by us, as Tyson recites part of the script that made the original Cosmos so awe-inspiring back in 1980:
We on earth marvel, and rightfully so, at the daily return of our single sun. But from a planet orbiting a star in a distant globular cluster, a still more glorious dawn awaits. Not a sunrise, but a galaxy rise. A morning filled with 200 billion suns, the rising of the milky way. An enormous spiral form with collapsing gas clouds condensing planetary systems, luminous super giants, stable middle aged suns, red giants, white dwarfs, planetary nebulas, super novas, neutron stars, pulsars, black holes, and, there is every reason to think, other exotic objects that we have yet to discover.
Or if you’re inclined to such foolishness, you could just let Carl Sagan “sing” it (warning: Autotune ahead. I think it works; your mileage may vary):
Cosmos: A Spacetime Odyssey airs on Fox 9:00 Sundays Eastern/Pacific, 8:00 Central/Mountain. Reruns Monday on National Geographic Channel 10:00 Eastern. Episode 8 “Sisters of the Sun,” online at CosmosOnTV.com