Astronomy
What Is the ISS? The International Space Station, Explained
The International Space Station is a crewed laboratory orbiting Earth at 17,500 mph. Here's what it is, who runs it, and how to see it from your backyard.
The International Space Station (ISS) is a crewed laboratory orbiting roughly 250 miles (400 km) above Earth. About the size of a football field, it circles the planet once every 90 minutes — traveling at around 17,500 mph — which means its astronauts see 16 sunrises and sunsets every day. It has been continuously lived in since 2000, making it humanity’s longest-running home in space.
What the ISS is for
The station is primarily a science lab. In its near-weightless environment, researchers run experiments that aren’t possible on the ground — studying how the human body adapts to space, growing crystals and tissues, testing materials, and observing Earth and the cosmos. It’s also a proving ground for the technology needed for longer missions to the Moon and Mars.
Who runs it
As the name says, it’s international. The ISS is a partnership between five space agencies: NASA (United States), Roscosmos (Russia), ESA (Europe), JAXA (Japan) and CSA (Canada). It was assembled in orbit piece by piece starting in 1998, and crews from many countries rotate through it.
How astronauts get there
Crews and supplies are ferried up by visiting spacecraft. SpaceX’s Dragon carries both astronauts and cargo, docking with the station and later returning to Earth — one of several vehicles that keep the ISS stocked and staffed.
How to see it from your backyard
Here’s the fun part: you can see the ISS with the naked eye. It looks like a very bright, steady star gliding silently across the sky over a few minutes — no twinkling, no blinking lights. It’s often one of the brightest things in the night sky. NASA’s free “Spot the Station” service tells you when it will pass over your location. While you’re out, it’s a great time to find the naked-eye planets too, and a pair of the best binoculars for stargazing will fill the wait nicely.
FAQ
What is the ISS in simple terms?
It’s a large, crewed science laboratory orbiting Earth, run by five international space agencies. Astronauts live and work aboard it, circling the planet every 90 minutes.
How fast does the ISS travel?
About 17,500 mph (28,000 km/h), fast enough to orbit Earth once every roughly 90 minutes — so the crew experiences 16 sunrises and sunsets each day.
Can you see the ISS from Earth?
Yes. It appears as a bright, steady point of light moving smoothly across the sky over a few minutes. NASA’s free “Spot the Station” alerts tell you when it’s visible from your area.
Who owns the ISS?
No single country. It’s a partnership of five space agencies — NASA, Roscosmos, ESA, JAXA and CSA — that jointly built and operate it.
Spaceflight programs evolve over time, including plans for the station’s future. This explainer covers the durable basics and is reviewed periodically.