Track the space station live in class: a 40-minute lesson

The ISS right now

What learners will do

• Read a position as latitude and longitude, and find it on a world map.
• Work out speed from distance and time, using the station's own numbers.
• Explain why an orbit is a constant fall around Earth, and why the path drifts west on each lap.

Set up (5 minutes)

• Open this page on the classroom screen: the map and the numbers below move live, nothing to install.
• Print the tracking sheet below, one per learner or pair.
• Ask first: where do you think the space station is right now, and how long would it take to fly around the world?

Track it (20 minutes)

• Every 5 minutes, read the latitude and longitude off the screen and write them with the time. Name the country or ocean underneath.
• Mark each position on the sheet's map grid and join the dots: that is the ground track.
• Write down the altitude and the speed in km/s. Does the speed change between readings? (Hardly: the orbit is nearly a circle.)
• Compare two readings 10 minutes apart: how many degrees of longitude did it cross?

Work it out together (10 minutes)

• Speed: about 7.7 km/s. Times 3,600 seconds is about 27,600 km/h, or 17,000 mph: London to New York in about 12 minutes.
• One lap: Earth's circumference at the station's height is about 42,700 km. Divided by 27,600 km/h is about 93 minutes.
• Laps a day: 24 hours divided by 93 minutes is about 15.5. Astronauts see 16 sunrises a day.
• Why does each lap pass further west? Earth turns under the orbit: 15° in every hour, so about 23° per lap.

Wrap up (5 minutes)

• Why does the station not fall down? (It does fall, all the time, but it moves sideways so fast that the ground curves away as fast as it falls.)
• Where will it be when the bell rings? Predict from the ground track, then check on the screen.
• Homework idea: see it with your own eyes tonight with the space-station watching lesson.