The International Space Station is often the third-brightest thing in the night sky, after the Moon and Venus. You need no telescope and no binoculars, just the right few minutes and the right direction.
The International Space Station is often the third-brightest thing in the night sky, after the Moon and Venus. You need no telescope and no binoculars, just the right few minutes and the right direction. This lesson explains why you can see it at all, why it only appears around dusk and dawn, and how to read a pass prediction so you are looking at the right patch of sky.
The ISS makes no light of its own. You see it because its huge solar arrays, spread across an area about the size of a football pitch, reflect sunlight down to you.
Astronomers measure brightness in magnitudes, where lower numbers mean brighter. The brightest star, Sirius, is about magnitude −1.5, so the ISS at its best outshines every star in the sky. Even a dim pass is easy to see from a city centre.
The station's orbit is tilted at 51.6 degrees to the equator, so it passes over everywhere between about 52° north and 52° south. Whether you can see it on a given night depends on that orbit lining up with your twilight.
A pass prediction gives you four things. Each one tells you something about how good the pass will be.
You need a telescope to see the space station.
Your eyes are all you need. A telescope is far too hard to aim at something crossing the sky in a few minutes.
It is visible any time it passes overhead.
Only when it is sunlit and your sky is dark. A daytime pass or a midnight pass in Earth's shadow cannot be seen.
You now know why the ISS only appears around dusk and dawn, why it comes in runs, and how to read a pass prediction. The visibility page shows tonight's passes for your town, with times, directions and how bright each one will be.