Five teachable Cosmos moments

TV’s new Cosmos series is filled with examples of first-rate science education

In Cosmos: A Spacetime Odyssey, Neil deGrasse Tyson takes on everything within the Milky Way, and far beyond it, too.

ForestWander/Wikimedia Commons (CC BY-SA 3.0 US)

Cosmos: A Spacetime Odyssey is the sweeping documentary television sequel to Carl Sagan’s iconic 1980 series. With all of space and time to explain, host Neil deGrasse Tyson has a difficult job shoehorning it comfortably into the 13-hour series. The origin of the universe, natural selection, black holes and photosynthesis are just a few of the topics this astrophysicist touches on in the shows, which premiered on Fox and National Geographic channels last month.

The episodes tend to jump from topic to topic. Viewers looking for a single story of the universe will be disappointed. Only a few episodes had a truly coherent narrative, dwelling on a single scientist or finding. Those with the strongest narratives aren’t necessarily the most successful at explaining science concepts. Others have excellent explanations, but don’t make a compelling story. Although I’d argue that every episode is worth watching, a few segments really stood out. If you don’t have time to invest in the whole series (at least not yet), you might want to sample these first.

Episode 1: Standing up in the Milky Way

Tyson launches the series with a short, beautiful explanation of science. “Test ideas with experiment and observation,” he says. “Build on those ideas that pass the test. Reject the ones that fail. Follow the evidence wherever it leads. And question everything.” This, in fact, sets the tone for the series.

The opening episode continues with an introduction to the solar system and to what we know, or think we know, about the universe.  Tyson employs the “Powers of Ten” technique to help viewers understand the size of the universe. It is a tried and true method that dates back to an essay by Kees Boeke in 1957. But it remains effective for first-time viewers. The episode concludes on an inspirational note, with Tyson telling the story of his first encounter with Sagan. He credits the astronomer and renowned science communicator with inspiring Tyson to become the scientist he is today.

Episode 2: Some of the things that molecules do

In episode two, Tyson tackles Darwin’s theory of evolution by natural selection. He begins with artificial selection, much as Darwin did in his book On the Origin of Species. Tyson explains how humans artificially selected wolves for key social traits over many years, eventually turning them into dogs. He then applies the concept to natural selection using the example of the polar bear. The episode offers a simple, but fascinating view of evolution. It emphasizes how DNA mutations at an individual level can scale up, resulting in changes to a whole population of organisms. Many explanations of evolution get bogged down in the details, but this one flows easily while remaining understandable.

Episode 6: Deeper, deeper, deeper still

This episode explores atomic structure, which was referred to but not explained in episode five. Tyson explains why carbon, and its flexible bonding abilities, is so essential to life on Earth. He also takes the viewer briefly through the states of matter, with a well animated vision of water at the molecular level. The excellent animations are especially helpful, showing clearly what scientists currently understand about atomic structure. Many lessons on atomic structure are framed as a history of atomic theory, running through Dalton and Thompson and Bohr. While this episode pays attention to Democritus and atomism, it spares viewers the rest of the history, relying on the most modern model (avoiding confusion with older ones).

Episode 8: Sisters of the sun

Many great men have contributed wonderful things to science. But great women also provided substantive contributions that too often are all but ignored. This episode attempts to rectify those omissions by focusing on talented women such as Annie Jump Cannon, Henrietta Swan Leavitt and Cecilia Payne, sharing their contributions to our knowledge of the stars. This segment — and others highlighting scientists such as the Arab mathematician and astronomer Ibn al-Haitham (episode 5) and the Chinese philosopher Mozi — show that not all of the major players in science were white European men.

Episode 12: The world set free

Here Tyson tackles climate change. But the highlight of this episode is his explanation of the difference between weather and climate. All he has to do is walk a dog. The inquisitive dog’s path wiggles back and forth, while Tyson continues to walk a straight line. The dog’s movements represent weather; Tyson’s symbolize climate, the smoother trend over time. The explanation is simple, but the impact is enormous.

These are just a few of the many fantastic moments in the new Cosmos series. If you watched the series, which moments stayed with you? Which episodes did you feel provided the most educational value and why? Share your thoughts below.

You can check out the newest episodes for a limited time at, or access the entire series on Hulu, Amazon or Netflix.

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Power Words

atom    The basic unit of a chemical element. Atoms are made up of a dense nucleus that contains positively charged protons and neutrally charged neutrons. The nucleus is orbited by a cloud of negatively charged electrons.

carbon  The chemical element having the atomic number 6. It is the physical basis of all life on Earth. Carbon exists freely as graphite and diamond. It is an important part of coal, limestone and petroleum, and is capable of self-bonding, chemically, to form an enormous number of chemically, biologically and commercially important molecules.

climate  The weather conditions prevailing in an area in general or over a long period.

climate change  Long-term, significant change in the climate of Earth. It can happen naturally or in response to human activities, including the burning of fossil fuels and clearing of forests.

evolution   A process by which species undergo changes over time, usually through genetic variation and natural selection, that leave a new type of organism better suited for its environment than the earlier type. The newer type is not necessarily more “advanced,” just better adapted to the conditions in which it developed.

solar system  The eight major planets and their moons in orbit around the sun, together with smaller bodies in the form of dwarf planets, asteroids, meteoroids and comets.

Weather  Conditions in the atmosphere at a localized place and a particular time. It is usually described in terms of particular features, such as air pressure, humidity, moisture, any precipitation (rain, snow or ice), temperature and wind speed. Weather constitutes the actual conditions that occur at any time and place. It’s different from climate, which is a description of the conditions that tend to occur in some general region during a particular month or season.

Bethany Brookshire was a longtime staff writer at Science News Explores and is the author of the book Pests: How Humans Create Animal Villains. She has a Ph.D. in physiology and pharmacology and likes to write about neuroscience, biology, climate and more. She thinks Porgs are an invasive species.