Introduction of space immigrants

Due to the rapid expansion of the world population, the earth is becoming more and more crowded, so scientists put forward the idea of building a space city. A design scheme of space city proposed by American scientists is a rotating cylinder with one end facing the sun and the other half spherical. A cylindrical space city with a radius of 100 m and a length of 4000 m can accommodate about 100 residents. Another design scheme is a space city rotating around wheels. The space city has a total diameter of 2800 meters, and the rim itself has a diameter of 300 meters. The outer edge of the wheel is the ground of the space city, and the inner edge of the wheel is the top of the space city. The "roof" is made of transparent material, and sunlight shines through the skylight. The adjusted space city is bright and warm as spring.