Episode 6 Recap: Finding Our Place in the Universe

Last Updated by Genius by Stephen Hawking Editor on
Nicolaus Copernicus
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Editor's Note: Sometimes, even the brightest minds need a helping hand. Can you think like a genius but still need a quick overview of the knowledge you just absorbed? Every week we'll highlight key terms from the show's episodes, as well as the geniuses of our past who were featured in the series.

Wrapping up their scientific journey, the volunteers discover where we exist in the universe.


Light-year: A light-year is the distance that light travels in one year. It moves at 186,000 miles a second, which is approximately 5.8 trillion miles per year. A light-year is used to measure distance — not time — on an astronomical scale.

Andromeda: A spiral galaxy like the Milky Way, Andromeda is the closest to our own galaxy. It can also be seen from Earth and is approximately 2.5 million light-years away from our planet. It has been reported that the Milky Way and Andromeda will eventually collide with one another in passing.

Historical Figures

Eratosthenes: A philosopher, mathematician and geographer, Eratosthenes made an important discovery about our Earth. After hearing that in Syene, Egypt (now Aswan) the sun would cast no shadow as it shone directly over a well at noon on the longest day of the year, he found that the opposite would happen in Alexandria where shadows were cast at an angle. Comparing the position of the sun’s rays in these locations, he was able to measure the diameter of the Earth.

Aristarchus: An astronomer and mathematician, you may recognize Aristarchus’s name since a large crater on the moon is named after him. He also proposed a model where planets revolved around the sun and was made leaps and bounds with his measurement of the moon.

Copernicus: Though not the first to propose the idea of a sun-centered universe like his predecessor Aristarchus, Copernicus created the Heliocentric model which is well recognized today. This model, which did not put Earth at the center, was generally more accepted during his time.

Leon Foucault: The French physicist is recognized for the Foucault pendulum, which demonstrates the rotation of the Earth.

Pendulum Experiment The Earth rotates, and where you are changes how you see the universe.

Learn About Episode 6

Learn About Episode 6

In this episode, the volunteers attempt to discover where we really are in the universe.

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