diff --git a/astronomy/README.md b/astronomy/README.md
index 8a08938..32b8705 100644
--- a/astronomy/README.md
+++ b/astronomy/README.md
@@ -140,8 +140,8 @@ instance.
 * `sunset(variant: int = 0)`
 * `moonrise(variant: int = 0)`
 * `moonset(variant: int = 0)`
-* `tstart(variant: int = 0)` Twilight start
-* `tend(variant: int = 0)` Twilight end
+* `tstart(variant: int = 0)` Twilight start, Sun about to rise.
+* `tend(variant: int = 0)` Twilight end, (Sun has set).
 * `is_up(sun: bool)-> bool` Returns `True` if the selected object is above the
 horizon.
 * `has_risen(sun: bool)->bool` Returns `True` if the selected object has risen.
diff --git a/astronomy/sun_moon.py b/astronomy/sun_moon.py
index 683ca86..898a00d 100644
--- a/astronomy/sun_moon.py
+++ b/astronomy/sun_moon.py
@@ -249,10 +249,10 @@ class RiSet:
     def moonset(self, variant: int = 0):
         return self._format(self._times[3], variant)
 
-    def tend(self, variant: int = 0):
+    def tstart(self, variant: int = 0):
         return self._format(self._times[4], variant)
 
-    def tstart(self, variant: int = 0):
+    def tend(self, variant: int = 0):
         return self._format(self._times[5], variant)
 
     def moonphase(self) -> float: