Printable worksheet · Grades 9 to 12 · about 20 minutes
How long does the ISS take to orbit the Earth?
A one-page worksheet using the space station's live height and speed: circumference, speed and time, and why the velocity of an orbiting object changes.
Numbers
Today's numbers come from the Live ISS tracker, captured when this page loaded: 18:34 UTC on November 3, 2026. Print the class set in one go so every copy matches the teacher notes. Reload for new numbers.The boxes are left blank. Students open the Live ISS tracker and copy in the numbers themselves, so answers vary a little: the teacher notes give the method and the range to accept.Live numbers are not available right now, so the boxes are blank: students look them up in the Live ISS tracker.
Orbital Radar · Space for Schools
Grades 9 to 12 · HS-ESS1-4
How long does the ISS take to orbit the Earth?
The International Space Station (ISS) moves in a circle around the center of the Earth. Use today's numbers to work out how long one lap takes.
Name Class Date
Today's numbers from the Live ISS tracker, 18:34 UTC on November 3, 2026write them in from orbitalradar.com/iss-tracker
Height of the ISS above the ground
435 km
Speed of the ISS
7.65 km/s
Radius of the Earth (fixed)
6,371 km
Open orbitalradar.com/iss-tracker and copy the height and speed it shows right now.
Add the Earth's radius to the height of the ISS. This is the radius of its orbit.[1]
km
How far does the ISS travel in one lap? Use: circumference = 2 × π × radius.[2]
km
How long does one lap take, in seconds? Use: time = distance ÷ speed.[2]
s
Change your answer to minutes.[1]
minutes
How many laps does the ISS make in one day (24 hours)?[2]
laps
Challenge. The ISS moves at a steady speed, but its velocity changes all the time. Explain why, and name the force that keeps it in orbit.[3]
Extension A satellite in a higher orbit moves more slowly. Does it take more or less time to go round the Earth? Give two reasons. [2]
Check: your answer to question 4 should be between one and two hours.
Teacher notes and answersNot on the student sheet. Printed only with "Print with answers".
Teacher notes: How long does the ISS take to orbit the Earth?
Worked from the numbers on today's sheet: height 435 km, speed 7.65 km/s (18:34 UTC on November 3, 2026).
Students looked up their own numbers, so answers vary a little: check the method and accept the range below.
Total 11 points, plus 2 for the extension.
Answers
Earth's radius + height: 6,371 + 435 = 6,806 km
2 × π × radius = 42,763 km (1 for the method, 1 for the answer)
distance ÷ speed: 42,763 ÷ 7.65 = 5,590 s
seconds ÷ 60 = 93.2 minutes
1,440 minutes in a day ÷ minutes per lap = 15.5 laps (accept 15 or 16 with working)
Velocity has a direction as well as a size. Moving in a circle, the direction changes all the time, so the velocity changes even though the speed does not. The force is gravity, the Earth's pull, towards the center of the Earth.
Extension: more time. The lap is longer (a bigger circle) and the satellite moves more slowly.
Watch for
Forgetting to add the Earth's radius: that gives about 6 minutes.
Using the diameter, or mixing kilometers and meters.
The range to accept
The ISS sinks slowly in the thin air at its height and is boosted from time to time, so its height changes a little from day to day, and its speed varies slightly round each lap. Any answer from 92 to 94 minutes is right.
Curriculum
NGSS HS-ESS1-4 (motion of orbiting objects, including human-made satellites). AP Physics 1: 2.9 Circular Motion.
How these worksheets work
One page, free to print and copy for teaching. The numbers on the sheet are captured from the live tool when the page loads, and printed with the time, so a class set printed together matches the teacher notes. Reload for new numbers.
No sign-in, no ads, and nothing for students to install.
Orbital Radar · Space for Schools