Spanning a diameter of 300 million kilometres, a circumference of 942.48 million kilometres and a width of 2 million kilometres, the Ringworld features a habitable Earth-like environment which spans an immense area of 1880 trillion square kilometres over its entire inner surface. This unimaginably huge area is almost 3.7 million times the total surface area of the Earth! This is like having 3.7 million Earths all mapped flat and joined edge to edge. With an average thickness of 40 kilometres and with an average density that is similar to the Earth’s crust, the Ringworld is estimated to have a total mass of about 33000 times the mass of the Earth or about 10 percent the mass of our Sun.
Rim walls that are over a thousand kilometres high are found along the edges at the inner surface of the Ringworld. These walls keep the atmosphere within the inner surface of the Ringworld by preventing the atmosphere from slipping off the edge into space. The Ringworld is so huge that journeying from one rim wall to the other will mean covering a distance that is equal to circling the Earth 50 times. Additionally, circumnavigating the entire Ringworld will mean covering a vastly greater distance that is equal to circling the Earth 23500 times. Travelling at a speed of one kilometre per second, it will take almost 30 years to completely circumnavigate the Ringworld!
The enormous size of the Ringworld allows equal scale maps of entire worlds to be reconstructed on its surface. If all the continents of the Earth were reconstructed to scale in one of the Ringworld’s many great oceans, the entire archipelago of continents will span only one percent the width of the Ringworld. To generate an Earth-like gravity on the inner surface of the Ringworld, the entire megastructure will have to spin at a rate of once every 777000 seconds. At this spin rate, the rim of the structure will be travelling at a speed of 1210 kilometres per second.
Interior to the Ringworld and located at a closer distance to the central sun, an enormous ring of equally spaced rectangular shades block the sun at regular intervals to provide a day-night cycle along the habitable inner surface of the Ringworld. During the day on the inner surface of the Ringworld, the sun always appears directly overhead and night arrives following an eclipse of the sun by one of the rectangular shades.
Between the Ringworld and its sun, a series of climate control shades are positioned into another ring which has the same spin rate as the Ringworld itself such that each climate control shade remains fixed over the same region of the Ringworld’s inner surface. These climate control shades block out various fractions of the Ringworld’s sun and create cold spots on the Ringworld’s inner surface which allow temperature gradients to be generated. These temperature gradients drive large scale atmospheric and oceanic circulations. Sufficient cooling by large enough climate control shades also lead to the creation of ice caps.