Guide
What is the International Space Station?
The International Space Station (ISS) is a crewed laboratory orbiting roughly 400 kilometers above Earth. It is the largest human-made structure in space — about the size of a football field — and has been continuously occupied by astronauts since November 2000.
How big is the ISS?
The station spans about 109 meters end to end, including its enormous solar arrays, and weighs around 420,000 kilograms. Inside, its pressurized modules offer roughly as much living space as a six-bedroom house, with laboratories, sleeping quarters, two bathrooms, a gym and a 360° viewing window called the Cupola.
How high and how fast does it orbit?
The ISS orbits in low Earth orbit at an average altitude of about 400 km (250 miles), travelling at roughly 28,000 km/h. At that speed it circles the entire planet once every 90 to 93 minutes — so the crew witnesses about 16 sunrises and 16 sunsets every single day. You can watch this happen on our live ISS tracker.
Who built it and who lives there?
The ISS is a partnership between five space agencies: NASA (United States), Roscosmos (Russia), ESA (Europe), JAXA (Japan) and CSA (Canada). It is typically home to a rotating crew of about seven astronauts and cosmonauts, who carry out scientific research that isn't possible on the ground.
Why does the ISS matter?
In microgravity, scientists study everything from how the human body ages to how fluids, flames and crystals behave without gravity's interference. The station is also a proving ground for the technology and human experience needed for longer missions to the Moon and, eventually, Mars.
See it for yourself
The ISS is visible to the naked eye as a bright, fast-moving point of light.