Field notes
Orbits, gravity and light
Short explanations, ideas to try, and the sources behind the science.
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.