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The earth is almost a closed system in terms of energy science. [wire connects planets]

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Except for some space junk and asteroids, barely anything affects the energy level [alien hovers near Earth]

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of the earth. There's one teeny tiny exception, of course: energy from the Sun. [Sun pictured]

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Well, the Sun is actually a reactor that generates nuclear energy 24x7. Well

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some of that energy reaches the Earth in the form of light, heat, and radiation. [energy moves to earth]

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Think about it: The Sun releases energy in every direction, only a small portion [energy from sun pictured]

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hits us, but that amount is enough to power our entire planet. For the longest

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time, solar power was the only power. The first squiggly little bacterium on the [person puts out solar panels]

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planet lived by converting sunlight into energy. Well today, all life on the planet [plants convert sunlight]

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either converts sunlight to energy directly, like plants, or eats stuff that

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does, like animals. Even if we weren't aware of it at the time, most of our [deer eats plant]

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technological history has been devoted to accessing the sun's energy more [people discuss invention]

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efficiently. The sun's heat causes the wind, which powers our windmills, right? [windmills pictured]

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Coal is just condensed dead trees which stored up sunlight for hundreds of years

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before shrinking into little black nubs. Oh, and fossil fuels like oil are [coal pictured]

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basically jellified animals from millions of years ago. And yeah, animal [animal jelly]

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jelly isn't the prettiest picture or even in the running for top 10 [animal jelly in museum]

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prettiest pictures, but hopefully the bigger picture is becoming clear. All the

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energy we can access here on earth came from the Sun if we trace it back far [energy storytelling]

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enough. So, let's take a second to see how humans have gotten at the sun's energy

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over time. Well, back in the hunter-gatherer age, it was mostly about [man lassoes energy]

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eating. Nope, humans didn't directly eat sunlight, though that would have saved us [person eats light]

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a lot of trouble. But plants captured the sun's energy, and humans ate plants, along [energy cycle shown]

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with animals that ate plants, or animals that ate other animals, which probably ate

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plants, which basically ate sunlight. Well, hunter-gatherers took the energy they

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got from eating and used it to do all their hunter-gathering hobbies, which of

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course mostly consisted of hunting, gathering, and the occasional public art [cave person in museum]

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project. Another big source of energy for hunter-gatherers became fire. [person lights fire]

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Early fire use let us burn up stored solar energy when and where we needed it.

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Mostly, this was for heat, light, and cooking. When we move on to the

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agricultural craftsman age, we find humans using both wind and water energy. [wind and water energy pictured]

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Windmills and watermills tap the energy of, yes, you guessed it, moving wind

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and water to save humans some sweat. Well, later the agricultural craftspeople

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added coal and coke. Coal wasn't a very big deal before the steam engine, but it [coal and coke pictured]

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was useful as a kind of super-condensed firewood. Coke was a refined coal which

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burned even hotter and powered furnaces to make iron. It also tasted terrible with

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burgers and fries. Once the Industrial Age hit, it was all about steam. Steam [person bites into coke]

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engines relied on heating up water and using the resulting steam to move gears

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and pistons. Well, at first they were just fancy water pumps, but steam engines were [steam engines pictured]

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in everything from trains to factories before long. Steam power could be

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used to turn a turbine and produce electricity. Well, like steam, electricity [steam engine diagram]

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started out small but eventually pervaded everyday life. Fossil fuels

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like petroleum, natural gas, and coal became really useful with the invention

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of the internal combustion engine. Most notably, the fossil fuels revolutionized [engine pictured]

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transportation. They're in cars, planes, and in cocktails at automaton bars. And once [robot drinks]

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we hit the post-industrial age, things so nuclear. Nuclear power is our first big [nuclear blast]

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step away from our reliance on the sun's energy. Well, it's a way of harnessing the

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energy that holds an atom's nucleus together. As a power source, it's been [nuclear power demonstrated]

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used to fuel electric plant. These days, there's also a push for newer, renewable

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sources of energy. Renewable energies include solar cells, fancy new [renewable energy pictured]

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wind turbines, biofuels, and geothermal. But they still make up a small amount of

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the world's total energy production. Of course, considering where we've come in [energy production diagram]

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such a short amount of time, anything seems possible, right? A cave person would

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have thought the best use of a solar panel would be to eat it. We've come a [cave person eats solar panel]

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long way.

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