This episode explores the nature of the greenhouse effect (discovered by Joseph Fourier and Svante Arrhenius), and the evidence demonstrating the existence of global warming from humanity's influence. Tyson begins by describing the long-term history of the planet Venus; based on readings from the Venera series of probes to the planet, the planet had once had an ocean and an atmosphere, but due to the release of carbon dioxide from volcanic eruptions, the runaway greenhouse effect on Venus caused the surface temperatures to increase and boiled away the oceans. Tyson then notes the delicate nature of the amount of carbon dioxide in the atmosphere can influence Earth's climate due to the greenhouse effect, and that levels of carbon dioxide have been increasing since the start of the 20th century. Evidence has shown this to be from mankind's consumption of oil, coal, and gas instead of from volcanic eruptions due to the isotopic signature of the carbon dioxide. The increase in carbon dioxide has led to an increase in temperatures, in turn leading to positive feedback loops of the melting polar ice caps and dethawing of the permafrost to increase carbon dioxide levels. Tyson then notes that humans have discovered means of harvesting solar power, such as Augustin Mouchot's solar-driven motor in the 19th century, and Frank Shuman's solar-based steam generator in the 1910's. Tyson points out that in both cases, the economics and ease of using cheap coal and oil caused these inventions to be overlooked at the time. Today, solar and wind-power systems would be able to collect enough solar energy from the sun easily. Tyson then compares the motivation for switching to these cleaner forms of energy to the efforts of the Space race and emphasizes that it is not too late for humanity to correct its course.

How does light escape from the sun? We take a journey from the center of the sun, following the path of light. We witness its fiery birth from in the core, its 430,000 mile battle against gravity and magnetism, and its escape from the solar surface.

It bursts from the Sun with the power of ten thousand nuclear weapons... and when it hits our planet, it could create the largest disaster in recorded history. A magnetic storm from the Sun could wipe out electrical power, television, radio, military communication, and nearly every piece of electronics in the Northern Hemisphere. It's a "Solar Katrina" -- a planet-wide "hurricane" of magnetic forces that scramble all 21st Century technology, possibly for good. What causes this magnetic superstorm? Why is magnetism so powerful -- and yet so poorly understood? And is there anything we can do to prevent the Magnetic Storm?

Once they were dreaded and thought to be dragons eating the sun--but modern science has dispelled mythology and we now look forward to total Solar Eclipses as one of the most spectacular phenomena in the heavens. Explore the complex movements of Earth, Moon and Sun that produce these unusual events and hear details why we may be the only intelligent beings in the known Universe to witness eclipses like we see on Earth. Man-made eclipses also figure into the science in the form of instruments called "coronagraphs." They blot out the sun and reveal its corona, uncovering secrets which, while enlightening, also warn of a disaster that could make our advanced technology crash and burn. Finally, travel into deep space, where the tiny eclipses caused by planets circling distant stars is now beginning to reveal hundreds more stars where "exoplanets" exist... perhaps even those in habitable zones like the Earth.

Our Sun has served Earth well for almost five billion years. It's bathed us with heat and energy. But like humans, our home star is mortal. In five billion years, it will stop nurturing its planetary offspring. The aging star will bloat out beyond the orbit of our planet incinerating all living things--including humans if we're still around.

A look at how the Sun was formed and how it could potentially die; its physical composition; how it makes energy; and the nature of solar eclipses, solar flares and sunspot activity. Behold the sun and all of its glory. Learn all things about the sun ranging from its beginning to its death. Also learn about how stars work in general and MUCH, MUCH more.