The space station passes so quickly through the sky because it orbits the Earth at 17,500 miles per hour. It is visible as a dot because it reflects sunlight, but during the day the sky is too bright for it to be seen. So you will only be able to spot it at dawn or dusk when there is enough sunlight for it to reflect but not so much that the sky drowns it out. How often you’ll be able to catch it from Earth depends on when it is dark where you are and when the station happens to pass over you, which NASA says can vary from several times a week to just once a month.
The app helps to spot the station using an augmented reality interface with a compass to help you point in the right direction to see the station, and also offers notifications for when viewing opportunities will be possible based on your location. If you snap a photo or video of the station using your phone, there’s also a way to share your images using the app.
“Even after 23 years of continuous human presence aboard the International Space Station, it’s incredibly exciting to see the station when you look up at just the right moment,” said Robyn Gatens, NASA’s International Space Station director. “The orbiting laboratory that continues to provide so many unique, tangible benefits for humanity really isn’t that far out of reach.”