People could live in space. 

People could live in space. 

These cities would be very big. They could hold many people. Some ideas are shaped like tubes. Others look like rings.
Space has lots of light. This light comes from the sun. We can use it for power. It also helps plants grow.
People could get supplies from the moon. They could find water and air there. This would help the cities stay alive.
Scientists have many big ideas. We have not built them yet. Would you live in a space city?
People have dreamed of living in space for a long time. 
Scientists have many ideas for how they might look. Some designs are shaped like large rings. These are called a Stanford torus. 

How would people survive out there? Space has plenty of light from the sun. This light can make power for the city. It also helps plants grow in farms. People could also get supplies from the moon or asteroids. This is called in-situ resource utilization. This means using what you find in space to make things like air and water. 
A space settlement is a large place built for people to live in outer space. 

Building a home in space is a very big job. 

Humans have imagined living in space for a very long time. 
In 1970, a physicist named Gerard K. O'Neill began working on these ideas. 

Space settlements could change how we live on Earth. They could provide a place for industry to move away from our planet. This might help protect the nature on Earth. People could also use resources found in space, such as mining asteroids. There is so much material in the asteroid belt that it could build habitats for trillions of people. 
A space settlement is a large-scale habitation facility located in outer space. Unlike a standard spacecraft or a temporary space station, these habitats are designed for permanent habitation. They might include closed ecological systems to support life over long periods. Some people call them space cities, space colonies, or space habitats. These structures could orbit the Earth or other celestial bodies. They might even be built within asteroids or serve as interstellar arks for traveling between stars. 
Designing a settlement requires solving many complex engineering problems. One major goal is creating artificial gravity through rotation. Large shapes like cylinders or rings spin to simulate the pull of gravity. These habitats must also manage a breathable atmosphere. This requires a specific mix of gases, usually 78% nitrogen and 21% oxygen. Nitrogen can be recycled almost perfectly, while oxygen might be extracted from lunar rock. 
Scientists have proposed several distinct types of settlement designs. One concept is the Bernal sphere, which is a large spherical habitat. Another is the Toroidal Colony, which uses a ring shape known as a Stanford torus. 

The history of these ideas began with science fiction. In 1869, Edward Everett Hale wrote "The Brick Moon," which was the first fictional treatment of a space habitat. 
In 1970, physicist Gerard K. O'Neill began a major era of research. He asked his students at Princeton University to calculate if large habitats were actually feasible. They discovered that giant cylinders made of steel and glass could work. This led NASA to sponsor summer workshops to study these concepts further. These studies explored how to protect residents from cosmic rays using radiation shielding. 

Space settlements offer massive potential for human growth and resources. The main asteroid belt contains enough material to build habitats with a surface area equal to 3,000 Earths. Using the free-floating resources of the entire solar system, some estimates suggest we could support trillions of people. Settlements could also provide easy access to solar energy. In Earth orbit, there are 1,400 watts of solar power available per square meter. This energy can be used for electricity, heat, and growing food for the inhabitants.
Living in space would also change how we interact with our solar system. Settlements could serve as bases for exploring other planets or moons. They could also act as passenger compartments for generation ships traveling to distant stars. 

🖼️ Images & Media (16)
+ 4 more
More to explore
✨ What else?
Related topics you might enjoy
🔬 Go deeper
More advanced topics to explore
🪜 Step back
Simpler topics to build understanding
What is Nepedia?
A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.