2D Animated Orbits

Now, let’s animate the orbit. Note that you have reset the argument of perigee to be 0 degrees.

Matplotlib’s FuncAnimation() takes a function and computes the next value given a range, plots the new value, waits a specified period of time, and then plots the next value. In your case, your animation is really just displaying the pre-computed X and Y coordinates of the orbit. You need to do some prep work to plot the orbit, plot the starting point of a red dot that will go around the orbit, and internally define an animate() function that accepts the incremental value i and returns (pos[i][1], pos[i][0]), so that the FuncAnimation() function can plot the new coordinates. Since pos[i] will give you the entire list of X or Y coordinates, you use the second [1] to get the X coordinates or [0] to get the Y coordinates of the nested list.