In which face the consequences of our own knowledge
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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.
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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
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
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!"
Halley's Comet is a good example of the random walk of history. Would the Normans have invaded England if Halley's comet that showed up at this convenient time? How different would all of western civilization been without William the Conqueror? We wouldn't consider beef an English word, that's for sure.
A nice example of the "interconnectedness of all things" is the story in this episode connecting the 12th-century monks with scientific results from the Apollo lunar missions.
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?"