diff --git a/scripts/plot-moon-illumination.py b/scripts/plot-moon-illumination.py
index 9634297..30e732e 100644
--- a/scripts/plot-moon-illumination.py
+++ b/scripts/plot-moon-illumination.py
@@ -38,7 +38,7 @@ def main():
 
     mask_altitude = moon.alt.to_value(u.deg) < 0
     moon_light = moon_illumination(time)
-    moon_light[mask_altitude] = 1
+    moon_light[mask_altitude] = 0
 
     fig, ax = plt.subplots()