diff --git a/demo/python/astronomy.py b/demo/python/astronomy.py
index baca2cc0..f3778846 100644
--- a/demo/python/astronomy.py
+++ b/demo/python/astronomy.py
@@ -420,6 +420,23 @@ class NoConvergeError(Error):
     def __init__(self):
         Error.__init__(self, 'Numeric solver did not converge - please report issue at https://github.com/cosinekitty/astronomy/issues')
 
+def PlanetOrbitalPeriod(body):
+    """Returns the average number of days it takes for a planet to orbit the Sun.
+
+    Parameters
+    ----------
+    body : Body
+        One of the planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, or Pluto.
+
+    Returns
+    -------
+    float
+        The mean orbital period of the body in days.
+    """
+    if isinstance(body, Body) and (0 <= body.value < len(_PlanetOrbitalPeriod)):
+        return _PlanetOrbitalPeriod[body.value]
+    raise InvalidBodyError()
+
 def _SynodicPeriod(body):
     if body == Body.Earth:
         raise EarthNotAllowedError()
diff --git a/generate/template/astronomy.py b/generate/template/astronomy.py
index 4125c9e0..2239f8fb 100644
--- a/generate/template/astronomy.py
+++ b/generate/template/astronomy.py
@@ -420,6 +420,23 @@ class NoConvergeError(Error):
     def __init__(self):
         Error.__init__(self, 'Numeric solver did not converge - please report issue at https://github.com/cosinekitty/astronomy/issues')
 
+def PlanetOrbitalPeriod(body):
+    """Returns the average number of days it takes for a planet to orbit the Sun.
+
+    Parameters
+    ----------
+    body : Body
+        One of the planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, or Pluto.
+
+    Returns
+    -------
+    float
+        The mean orbital period of the body in days.
+    """
+    if isinstance(body, Body) and (0 <= body.value < len(_PlanetOrbitalPeriod)):
+        return _PlanetOrbitalPeriod[body.value]
+    raise InvalidBodyError()
+
 def _SynodicPeriod(body):
     if body == Body.Earth:
         raise EarthNotAllowedError()
diff --git a/generate/test.py b/generate/test.py
index ab6ae1fb..75b8f4fc 100755
--- a/generate/test.py
+++ b/generate/test.py
@@ -1265,24 +1265,12 @@ def Refraction():
 
 #-----------------------------------------------------------------------------------------------------------
 
-PlanetOrbitalPeriod = {
-    astronomy.Body.Mercury:     87.969,
-    astronomy.Body.Venus:      224.701,
-    astronomy.Body.Earth:      365.256,
-    astronomy.Body.Mars:       686.980,
-    astronomy.Body.Jupiter:   4332.589,
-    astronomy.Body.Saturn:   10759.22,
-    astronomy.Body.Uranus:   30685.4,
-    astronomy.Body.Neptune:  60189.0,
-    astronomy.Body.Pluto:    90560.0
-}
-
 def PlanetApsis():
     start_time = astronomy.Time.Make(1700, 1, 1, 0, 0, 0)
     body = astronomy.Body.Mercury
     while body.value <= astronomy.Body.Pluto.value:
         count = 1
-        period = PlanetOrbitalPeriod[body]
+        period = astronomy.PlanetOrbitalPeriod(body)
         filename = os.path.join('apsides', 'apsis_{}.txt'.format(body.value))
         min_interval = -1.0
         max_diff_days = 0.0
diff --git a/source/python/README.md b/source/python/README.md
index d3012650..663732bb 100644
--- a/source/python/README.md
+++ b/source/python/README.md
@@ -2345,6 +2345,20 @@ A pivoted matrix object.
 
 ---
 
+<a name="PlanetOrbitalPeriod"></a>
+### PlanetOrbitalPeriod(body)
+
+**Returns the average number of days it takes for a planet to orbit the Sun.**
+
+| Type | Parameter | Description |
+| --- | --- | --- |
+| [`Body`](#Body) | `body` | One of the planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, or Pluto. |
+
+**Returns**: `float`
+The mean orbital period of the body in days.
+
+---
+
 <a name="RefractionAngle"></a>
 ### RefractionAngle(refraction, altitude)
 
diff --git a/source/python/astronomy/astronomy.py b/source/python/astronomy/astronomy.py
index baca2cc0..f3778846 100644
--- a/source/python/astronomy/astronomy.py
+++ b/source/python/astronomy/astronomy.py
@@ -420,6 +420,23 @@ class NoConvergeError(Error):
     def __init__(self):
         Error.__init__(self, 'Numeric solver did not converge - please report issue at https://github.com/cosinekitty/astronomy/issues')
 
+def PlanetOrbitalPeriod(body):
+    """Returns the average number of days it takes for a planet to orbit the Sun.
+
+    Parameters
+    ----------
+    body : Body
+        One of the planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, or Pluto.
+
+    Returns
+    -------
+    float
+        The mean orbital period of the body in days.
+    """
+    if isinstance(body, Body) and (0 <= body.value < len(_PlanetOrbitalPeriod)):
+        return _PlanetOrbitalPeriod[body.value]
+    raise InvalidBodyError()
+
 def _SynodicPeriod(body):
     if body == Body.Earth:
         raise EarthNotAllowedError()