In this clip from Genius by Stephen Hawking, the volunteers use light years to work out where our solar system is located in the universe. In 1838, German astronomer Frederich Bessel was able to calculate that a nearby star called 61 Cygni was around 67 trillion miles away from Earth. By observing this same star at different times throughout the year, Bessel was able to calculate the star's position in the sky using trigonometry. The distance was so great he had to create a new unit of measurement; light years. Using this unit of measurement, the volunteers work out how many light years away the planets and stars are in the solar system, but also how far away neighboring galaxies are.