diff --git a/kosmorrolib/events.py b/kosmorrolib/events.py
index 41e0e2d..4fd5ab3 100644
--- a/kosmorrolib/events.py
+++ b/kosmorrolib/events.py
@@ -80,7 +80,7 @@ def _search_oppositions(start_time: Time, end_time: Time) -> [Event]:
     events = []
 
     for aster in ASTERS:
-        if not isinstance(aster, Planet) or aster.name in ['Mercury', 'Venus']:
+        if not isinstance(aster, Planet) or aster.skyfield_name in ['MERCURY', 'VENUS']:
             continue
 
         times, _ = find_discrete(start_time, end_time, is_oppositing)