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Cosmos with Cosmos Episode 4: Heaven & Hell

In which face the consequences of our own knowledge

Posted by Casey Dreier

04-11-2013 23:53 CST

Topics: product review, history, comets, fun, Earth impact hazard, Venus missions before 2000, personal stories, Venus Express, Venus, comet Halley, Planetary Society History

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 3: The
Harmony of the Worlds

Episode 5: Blues
for a Red Planet »

Halley's comet has caused a lot of trouble over the years. Wars, political upheavals, treachery, panic, and fear could all be expected in reaction to this pale swatch of starlight periodically upsetting the predictable night sky.

But 1986's encounter with comet Halley was different. Instead of greeting the comet with fear, it faced the cold analytical disinterest of six spacecraft representing the passionate interest of millions of people on Earth. These spacecraft, called "Halley's Armada" represented a joint effort by multiple countries to study all aspects of this troublesome comet.

The European Space Agency's Giotto and the USSR's Vega spacecraft returned close-up images of comet Halley for the first time in its history, pulling back the curtain on this terror-inducing apparition to reveal its true nature: a passive lump of ice and rock in the shape of a peanut.

Science dissipated our fear. The frightening unknown became the benign known: comets are just passing us by. The influence on human events were only the projections of our own actions, as subjective and meaningless as the patterns we impose on the stars to create the constellations.

But science has also brought about a new fear – this time utterly legitimate – that comets and their asteroid cousins have a far greater ability to alter human affairs than the mere toppling of  some local kingdom; they can destroy all human civilization and even all life on Earth via a large impact. The recession of one fear ushered in another: the insecurity of our existence. The knowledge that one day we may face our own demise, that, as Sagan says, "is improbable in a hundred years [but] inevitable in a hundred million." This parallels the path of comprehending our own mortality, the inevitable price of self-awareness that has long troubled the human condition.

The Hebrew bible's Garden of Eden and similar myths from other cultures epitomize this transition. Knowledge drives us out of our comfortable existence. Though as we saw with people's reaction to the appearance of comets, ignorance isn't always paradise, but it sure requires a lot less responsibility.

In Episode 4 of Cosmos, Heaven & Hell, Sagan narrates our own civilization's departure from this Eden. Starting with the destructive comet impact of the Tunguska event (all the more immediate nowadays in the aftermath of Chelyabinsk) and continuing into global nuclear war and climate change, we are reminded again of the price we pay for leaving ignorant superstitions behind.

But this is Cosmos, so there's a lot more than just comets to discuss this week. Sagan takes us through a tour of the inner solar system, describing the difference between gas giants and terrestrial planets. We learn about the electromagnetic spectrum and get a satisfying takedown of Immanuel Velikovsky's strange theory that Venus was a "comet" spat out from the planet Jupiter, responsible for a variety of ancient biblical miracles. I'm assuming this was a more prominent part of the zeitgeist when this was first filmed than it is now. If I had to guess, I would say that we will not see this revisited in the new Cosmos.

One useful thing about Velikovsky's theory is that it provides the thematic bridge between comets and Venus (thanks Velikovsky!) and we are able to spend some time appreciating the hell that is our near neighbor, Venus.

There are a surprising number of people who don't realize that human beings have landed robotic spacecraft on the surface of Venus (I fear this may have to do with a certain NASA-centric chauvinism of many Americans). The Soviets landed on Venus six times, returning all the images we have of the surface of planet. The images are eerie and spectacular, and I recommend you take a moment to read about them on Don Mitchell's comprehensive website.

The first discoveries about the nature of Venus (and Mars) helped create the new field of comparative planetology, one of the more compelling consequences of planetary exploration. We have, next to Earth, two examples of planets gone horribly wrong. Mars's atmosphere has disappeared, and with it, its water. Venus's atmosphere has spiralled out of control, trapping in the heat that led to its hellish environment.

Venera 10's landing site

Ted Stryk

Venera 10's landing site
Venera 10 landed on October 25, 1975. The terrain at Venera 10's landing site is smooth and platy.

As with comets, we've come to understand the true natures of Venus and Mars. They lost their astrological significance with the dawn of the renaissance, but the consequence is our knowledge that climates can change, that nothing – even our comparative heaven of Earth – is permanent. That's a heavy burden. We now have the responsibility to maintain our heaven; we have two examples of what can go wrong.

But can we bear this responsibility? Episode 4 introduces another major theme of the series: our own role in maintaining our presence in the cosmos. Sagan was an early proponent of action in response to global climate change and in nuclear disarmament. Both are threats posed by our new technological capability, and both require sacrifice and restraint in the short term if we are to survive in the long term.

"The doors to heaven and hell are adjacent and identical," says Sagan early in this episode. This is a quote from Nikos Kazantzakis's novel The Last Temptation of Christ, a somewhat controversial but fascinating look into human temptations. Sagan and his writers are well-read and this quote was surely meant to take on additional meaning when examined in context.

The last temptation Jesus faces is to live a happy, fulfilled life as a man – rejecting his own self-sacrifice and its importance to the larger world. He is removed from the cross during his crucifixion and, the pain gone, is led away and into a simple life as a farmer and husband. The weight of the world off of him, he forgets his old teachings and ideas and removes himself from the machinations of the world. Ultimately (of course) he reverses himself and realizes the deception for what it is, choosing the reality of the painful sacrifice and rejecting the seductive fantasy.

Kazantzakis was fascinated by Jesus's metaphorical relationship to humanity. Every person faces similar, if less extreme, choices throughout their lives. Are we able to transcend our immediate desires for what we want to be true and accept reality? How can we overcome our own seduction into falsehood?

As Sagan understood, we now face these questions as a civilization. Do we embrace the hard truths of global climate change, the ones that demand us to sacrifice parts of our pleasant way of life for an ambiguous long-term benefit? Or do we choose the tempting denial that requires us to do nothing except enjoy our lives? Do we arm ourselves to the teeth and risk losing everything in "meaningless self-destruction," or do we find ways to give up the posturing behind the pride of nation-states?

The Great Chelyabinsk Bolide of February 15, 2013

Don Davis

The Great Chelyabinsk Bolide of February 15, 2013
This was the greatest known impact event on Earth since the 1908 Tunguska event. Now, as then, a small asteroid (or huge meteor) entered the atmosphere and exploded in the air, sending a shockwave out and down. This time, an object about 18 meters (54ft) across entered the atmosphere, again in the Siberia region, at 03:20:33 GMT at a shallow angle. It seared a luminous path in a Northwestern direction across the skies of a cold late Winter morning in the Ural Mountain region. As it encountered denser air the meteor slowed down, with enormous energy being unleashed upon the rocky body, climaxing with an extended explosive energy release at some 23.3 km (14.5 miles) altitude over 54.8 degrees N, 61.1 degrees E. This long brilliant burst peaked in brightness briefly lighting up the region brighter than sunlight, with people nearby feeling the radiant heat.

Humans have unlocked the secrets of technology to greatly benefit our lives. The unavoidable (and strangely poetic) corollary is that this same technology directly and indirectly threatens to destroy us. Access to this knowledge requires a certain level of maturity that we are still developing, trying to balance the best of ourselves against the worst. We're the Adam and Eve who left the sweet ignorance of Eden, now fully understanding the possibility of our own death. But we also gained self-determination and a certain level of self-awareness. Nothing is inevitable.

The Kazantzakis quote in the episode is worth examining in context: Jesus is dreaming of Adam in the Garden. Birds are speaking to him, boasting of their abilities and their perceived importance. Adam reclines against a tree, relaxed and more or less ignoring the procession. But then a blackbird lands on his shoulder and leans into his ear, urgently whispering a message of far more importance: "the doors to heaven and hell are adjacent and identical: both green, both beautiful," it warns him. "Take care Adam! Take care! Take care!"

Stray Observations

Science Update

  • The current accepted theory for the creation of the Moon is that a Mars-sized impactor slammed into the Earth at a very early stage in its history – far more dramatic than just coalescing from debris at the same time as the Earth.
  • NASA's last mission to Venus was Magellan, launched in 1989, which mapped the entire surface with high-resolution radar and suggested that the surface of Venus is quite young by geologic standards – around 800 million years old.
  • ESA is currently the only space agency with a spacecraft at Venus, the 2005 Venus Express, sent to study the interactions between the Venusian atmosphere and solar winds.


  • "It's a strange scenario, a comet hits the Earth and the response of our civilization is to promptly self-destruct."
  • "There were entrepreneurs hawking comet pills... I think I'm going to take one for later [slips it into pocket]."
  • "Our generation must choose. Which do we value more? Short term profits or the long term habitability of our planetary home… We have uncovered other worlds with choking atmospheres and deadly surfaces. Shall we then recreate these hells on Earth? We have encountered desolate moons and barren asteroids. Shall we then scar and crater this blue new world in their likeness?"
« Episode 3: The
Harmony of the Worlds
Episode 5: Blues
for a Red Planet »

See other posts from November 2013


Or read more blog entries about: product review, history, comets, fun, Earth impact hazard, Venus missions before 2000, personal stories, Venus Express, Venus, comet Halley, Planetary Society History


Dan Cook: 11/05/2013 09:02 CST

Really well done. Without going into too much detail here, I see whole cities making this short term trade off for oil and gas jobs every day. My own financial security is loosely based off of it at the moment. I know of no one at present with a family to support who woild turn down the amount of money some of these jobs provide for the middle class. It can be a blight on the soul as well as the planet.

Torbj??rn Larsson: 11/05/2013 12:33 CST

[A link to Schaller's post on Cosmos art may be considered part of the discussion: ] I wonder what Sagan would have thought of then young climate science already surpassed medicine at 2 sigma and now entering physics quality of validating AGW at 3 sigma [IPCC -13], or that we already have observed other systems with 3 planets in the habitable zone [ Habitable Exoplanets Database] akin to our own? Granted, part of the climate science quality comes from a now huge signal-to-noise ration, but also from much improved modeling. In fact, I just read how such detailed models predict a habitable Archean climate as well as possible later slush ball episodes for the first time in one paper, thus explaining our own habitability until today, and I have a 2nd paper in the read stack that promises even better predictions. Odds & ends: - Mars atmosphere. As described elsewhere on PlanSoc, maybe only 200 million years of atmosphere dense enough for an ocean. Would still have got life started, Mars has plenty of hydrothermal vents even today, but has it retreated safely? I heard the atmosphere may have been removed by the crust making carbonates. [Haven't got around reading that yet.] - Saturn rings. The last I heard was that secular evolution of initial icy moons would push some to disintegrate and predict the seen rings. [Didn't bookmark, so no ref; YMMV.] - Velikovsky and Shuttle. Honestly, I had forgotten about those. Time flies.

Torbj??rn Larsson: 11/05/2013 12:43 CST

Finally, two poorer choices re me personally: - "they can destroy all human civilization and even all life on Earth via a large impact." Not likely on the first and unrealistic on the second. 1. Homo species have lived 2 million years max (the amazingly robust H. erectus), and we evolve faster than most due to our vast population size (makes selective sweeps works more efficiently). The reasonable MTBFs (say, failure as in mass extinctions) are a lot larger than that. 2. Mojzcics [sp?] et al modeled this for the first time I know of, and even mesophiles survived 10x the rate of the late bombardment. These author's may have to update with the GRAIL daya on how beaten up the Moon crust is, but the point is that prokaryotes procreate and spreads faster than any reasonable rate. A 2nd paper showed that even crust busters poses no problem, since there is an inhabited Goldilock zone ~ 1 km down that survives ocean evaporation. Life is a plaque on a planet. You can't kill it except by also destroying, kill, the planet. - Abrahamistic myths. I think Sagan illustrated how these have only inspired for bad, never for good (burning the last version of the Alexandrian library; similarly with a vast Asian library I forgot the name for), and how they have harassed science. Why not pick something nicer in this particular context, like the Yule goat and his sacrifice for others (presents), which doesn't alienate readers? I like Yule. =D

Jimi Maze: 11/06/2013 09:58 CST

slight grammar error: "There were entrepreneurs hawking comet pills... I think I'll going to take one for later [slips it into pocket]."

Jimi Maze: 11/06/2013 10:46 CST

I hope new Cosmos reviews the 1986 Halley's Comet missions. I had no idea whatsoever that Sagan was referencing "Last Temptation of Christ" whatsoever. I recall the first time I wikipedia'd Sagan in 2004, I was shocked to find an article, not about his beautiful philosophies on science and his vast knowledge, but rather, that he was "an Atheist" who attacked religion in general. I live up in Canada, and I was unaware that some people still take the Genesis as hard fact rather than metaphor. I am glad now that the current Sagan wikipedia better reflects his positive nature and accomplishments. I have a hypothesis that Earth, as a life-form, is shooting sperm to the other planet eggs. All the politics of rockets and weaponry and "Korolev vs. von Braun" is simply an alternative and complicated angle on the bigger simple mission of Earth wishing to spread her "life" virus to other planets and moons. Extremophile contaminants stowaway on our spacecraft and hope to survive and evolve on other worlds. Ah it's a hypothesis, I really enjoy reading a true scientist, your links, and everybody's comments and links. I live-tweet @jimimaze while watching #cosmos.

James Mueller: 11/07/2013 08:46 CST

I'm really enjoying watching the 1980 Cosmos Series. It was a great idea to break it into managable chunks of a chapter per week. It's also great timing that we will finish before the 2014 version of Cosmos starts on Fox TV. I watch the show on the Internet with Carl's "10 year later" update, then read the chapter from my book "Cosmos" that I bought 33 years ago, and finally read your blog and comments which always adds additional insights. Thoroughly enjoyable. Thanks.

Pradeep : 11/11/2013 01:08 CST

Sagan noted that the Sphinx is 5550 years old. They are now determined to be ~4500 years old

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