Orbital Motion

Read 3.4 Orbits in the Solar System to understand the paths celestial bodies take around the Sun.
It is more or less “natural” that the larger objects in our solar system would have more circular orbits while the smaller objects would have more elliptical orbits. To see how this arises, watch Simulating Orbits in a Solar System which uses the “Create Solar Nebula” option in our Gravity Simulator.
Explore 3.5 Motions of Satellites and Spacecraft for insights into how artificial satellites orbit Earth and the dynamics of interplanetary travel.
The connection between “orbit” and “free-fall” is kind of strange. For an illustrated explanation, check out the TED-Ed video Free falling in outer space.
The number of satellites that are currently in orbit above the earth is truly mind-melting. Check out this Low Earth Orbit Visualization to see a real-time view of the satellites in orbit. (Yes, this is real.) How are those satellites not hitting each other? Well, you’ve got to remember that the earth is really, really big, and satellites are generally pretty small (much smaller than they look on the visualization.
You can see satellites in the night sky every night - you just need to look up within a couple hours of sunset or sunrise. If you’re lucky, you may even catch a train of satellites that were launched together, just like I did back in 2019. You can see that I’m having a hard time containing my excitement.
Learn about 3.6 Gravity with More Than Two Bodies and the complexities of gravitational interactions in systems with multiple celestial bodies.
Here’s a nice, brief summary of Neptune’s Discovery Story, courtesy of our old pal, Neil deGrasse Tyson.
Before NASA launches a $100 million+ space mission, scientists and engineers carefully plot out the orbit of the spacecraft from launch all the way to touchdown. Those complicated calculations are carried out by sophisticated computers today, but in the 1960’s Apollo-era, the “calculators” were humans. The 2016 book and movie “Hidden Figures” tells the story of three African-American women who served as “calculators” at NASA during this time. Check out the video, We Met Katherine Johnson - One of the Real ‘Hidden Figures’ to see some of what the movie got right - and wrong.