Space science · Interactive experiments
How fast is fast enough to stay in orbit?
Give a satellite some sideways speed. See whether it falls, circles Earth or escapes.
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Read the science
Three questions to start with
What keeps a satellite in orbit?
A satellite keeps falling towards Earth while its sideways motion carries it around the planet.
Does gravity stop in space?
Getting above the atmosphere does not turn gravity off. Distance changes its strength.
How long does sunlight take to reach Earth?
At one astronomical unit, sunlight takes about 499 seconds to reach Earth. Here is the calculation.
Inside Orbit Lab
Change the speed
Compare the paths
The simulator starts above Earth, without engines or air resistance. Adjust speed and altitude, then try three short challenges: find a circle, stretch it into an ellipse and reach escape speed.
Start with a falling satelliteAn educational two-body model, with its assumptions and sources included.