Sunday marks the finale of Neil deGrasse Tyson's "Cosmos: A Spacetime Odyssey." Though the wonderful hours of being dazzled, stunned and educated by Tyson and his "Ship of the Imagination" are coming to a close, there is still plenty about our cosmos left to ponder. (Let's face it, we'll probably rewatch the series and learn something new with each subsequent viewing.)
Here are the most important scientific lessons from our astrophysicist pal, Neil deGrasse Tyson:
1) It's OK to not know all of the answers.
While it isn't an eye-opening, Earth-shattering revelation, knowing it's not OK to have all the answers may be one of the most important lesson from "Cosmos." If humans say "I don't know," then scientists can work on asking, "Why?" and then testing to solve the mystery.
"It's OK not to know all the answers," Tyson explains to the audience. "It's better to admit our ignorance, than to believe answers that might be wrong. Pretending to know everything, closes the door to finding out what's really there."
2) Climate change is happening, and it's man-made.
Climate change is a topic that Tyson tackles in several episodes. His most shocking and thorough admonition comes Episode 12, "The World Set Free," which tells the tale of two planets, Venus and Earth.
Though its sweltering climate was not caused by man-made forces, Venus is still a cautionary tale of a greenhouse-gas overload. The amount of carbon dioxide in Venus' atmosphere has turned the planet into an inferno. Even lead (melting point: 621.5°F) is a liquid on Venus. Tyson explains how, on Earth, humans have added 400 billion tons of CO2 into the atmosphere since Carl Sagan's original "Cosmos." While a climate as extreme as Venus' is unlikely in Earth's near future, we're certainly doing everything we can to catch up to our cosmic neighbor.
Tyson then refutes many arguments made by climate deniers:
Q: Could the carbon dioxide be coming from volcanoes?
A: A very small portion is, but this gas is slightly different than that of burning coal or fossil fuels, so scientists can recognize that most comes from man-made causes.
Q: But this winter was so cold. If scientists can't even predict the weather, how can they predict climate change?
A: Well, climate and weather are two different things. Weather events are short-term patterns in the atmosphere, and climate is a long-term trend.
Watch the clip here.
3) Evolution: How did we get here?
This lesson may seem like an obvious one. However, with creationists up in arms over the show's depiction of evolution, it turns out it was an important one.
From the first episode of "Cosmos," Tyson addresses evolution, and he continues to throughout the series. Evolution as a scientific theory is often vilified by religious groups who advocate for a strict interpretation of the Bible. However, it is important to Earth's future that folks understand the planet's past -- patterns of climate, examples of extinction, natural selection and how humans came to be. Life today could not have happened without the evolution that happened slowly over the 4.5 billion years of Earth's history.
The future of our planet relies on understanding how genes changed and mutated to fit their surroundings. An example comes from Episode 9, "The Lost Worlds of Planet Earth." This episode took viewers through the history of our Earth -- preserved through fossils, and layers of rock. Tyson explains the evolution of plants: A new material "lingin" allowed plants to grow taller and brought about the rise of the trees. Unfortunately, it took much longer for organisms to evolve to be able to decompose "lingin," and the solidification and burying of non-decomposed trees is why the planet has coal.
4) The danger of ignoring science, or following special-interest science.
Beyond poking scientific holes through creationist pseudo-science, "Cosmos" demands that viewers look closely at other scientific claims -- namely ones backed by big corporations.
In the seventh episode, "The Clean Room," Tyson's narrative does both. It follows the discoveries of California Institute of Technology researcher Clair Patterson. Patterson first set out to determine the age of the Earth, which he found to be 4.5 billion years old. In the process of making this discovery, Patterson noticed the prevalence of the toxic element, lead, in the surrounding environment. Lead had been contaminating his previous experiment, and caused him much frustration and the restarting of the process.
Patterson then set about researching the prevalence of lead in the environment, asking, "was this amount of lead natural, or introduced by man?" What he found was that harmful lead was being introduced to the environment. This finding challenged the oil industry's current product: leaded gasoline. The true story of how Clair Patterson fought the oil industry and its hired henchman-scientist, Robert Kehoe (a long and laborious process), shows how large corporations often try to discredit science. It also shows the importance of open-minded politicians, who are not bound by special interests. "This was one of the first times that the authority of science was used to cloak a threat to public health and the environment," Tyson explained.
5) Discovery starts with an open mind and the scientific method.
Though it seems simple, this may be the most important lessons from Tyson: How to think about, test and raise questions about the surrounding world. In the very first episode, Tyson explains that all the following scientific lessons were made possible due to a codified set of rules. To paraphrase, test ideas by observation or experimentation, build upon those that pass, reject those that prove false, follow the evidence no matter where it leads and never stop asking questions.
These rules, known as the scientific method, not only give the viewer context for the scientific wonders about to unfold, but they also give a blueprint for our own scientific discovery. The scientific method is again brought up in the fifth episode, "Hiding in the Light," and how scientists were eventually able to learn more about light, how it travels, non-visible wavelengths and a host of other discoveries. As usual, there is more than meets the eye.
From lesson No. 5, spring all the other lessons.