"## QUESTION 4: Edit the code below to create a two-panel plot that shows r and v as a function of theta\n",
    "# Things to include:\n",
    "# - axis labels\n",
    "# - reasonable units for r and v, I suggest au and km/s\n",
    "# Check that your plot is reasonable! Are you getting values you expect for r and v?\n",
    "\n",
    "# This code creates two plots side-by-side, horizontally. You can do two vertical subplots using plt.subplots(2,1). \n",
    "# Then 'ax1.plot' is used instead of 'plt.plot' for the plot on the left, and ax2 is used for the plot on the right. \n",
    "# Figsize can be adjusted to make your plots bigger and space them out better. \n",
    "fig, (ax1, ax2) = plt.subplots(1, 2, figsize=(10,4))\n",
    "ax1.plot()       # plot theta vs. r here in some units\n",
    "ax2.plot()   # plot theta vs. v here in some units\n",
    "# Fill in between the '' to create labels below; see your previous python assignment\n",
    "ax1.set_xlabel('0')\n",
    "ax2.set_xlabel('10')\n",
    "ax1.set_ylabel('-2')\n",
    "ax2.set_ylabel('2')\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Caption your plot here: "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 71,
   "metadata": {},
   "outputs": [
    {
     "ename": "SyntaxError",
     "evalue": "invalid syntax (<ipython-input-71-5847397ca432>, line 9)",
     "output_type": "error",
     "traceback": [
      "\u001b[0;36m  File \u001b[0;32m\"<ipython-input-71-5847397ca432>\"\u001b[0;36m, line \u001b[0;32m9\u001b[0m\n\u001b[0;31m    ekin =\u001b[0m\n\u001b[0m           ^\u001b[0m\n\u001b[0;31mSyntaxError\u001b[0m\u001b[0;31m:\u001b[0m invalid syntax\n"
     ]
    }
   ],
   "source": [