# 2D Animated Orbits

Learn how to plot 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`

.

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