diff --git a/src/machinevisiontoolbox/Sources.py b/src/machinevisiontoolbox/Sources.py
index efe1366a..5db0cbc8 100644
--- a/src/machinevisiontoolbox/Sources.py
+++ b/src/machinevisiontoolbox/Sources.py
@@ -1822,7 +1822,8 @@ class EarthView(ImageSource):
     """
     Iterate images from GoogleEarth
 
-    :param key: Google API key, defaults to None
+    :param key: Google Maps API key, defaults to None (read from the
+        environment, see note below)
     :type key: str
     :param type: type of map (API ``maptype``): 'satellite' [default], 'map', 'roads', 'hybrid', and 'terrain'.
     :type type: str, optional
@@ -1865,9 +1866,15 @@ class EarthView(ImageSource):
         `Getting started <https://developers.google.com/maps/documentation/maps-static>`_
 
     .. note::
-        - If the key is not passed in, a value is sought from the
-            environment variable ``GOOGLE_API_KEY``.
-        - Uses the `Google Maps Static API <https://developers.google.com/maps/documentation/maps-static/start>`_
+        - If ``key`` is not passed in, it is read from the environment
+          variable ``GOOGLE_MAPS_API_KEY``, or failing that from
+          ``GOOGLE_API_KEY``. Prefer ``GOOGLE_MAPS_API_KEY``: Google's Gemini
+          libraries also read ``GOOGLE_API_KEY``, so using that name for a
+          Maps key can hand the wrong key to one or the other.
+        - Uses the `Google Maps Static API <https://developers.google.com/maps/documentation/maps-static/start>`_.
+          Restrict the key to that API only (Google Cloud console, *APIs &
+          Services → Credentials*), so a leaked key can't be used for
+          anything else, and consider a daily request quota to bound costs.
 
     :references:
         - |RVC3|, Section 11.1.6.
@@ -1893,7 +1900,9 @@ def __init__(
     ) -> None:
 
         if key is None:
-            self.key = os.getenv("GOOGLE_API_KEY")
+            # GOOGLE_MAPS_API_KEY first; GOOGLE_API_KEY kept for backward
+            # compatibility (it's also the name Gemini libraries read)
+            self.key = os.getenv("GOOGLE_MAPS_API_KEY") or os.getenv("GOOGLE_API_KEY")
         else:
             self.key = key
 
diff --git a/tests/test_image_sources.py b/tests/test_image_sources.py
index 4f5cb2c0..1710fad8 100644
--- a/tests/test_image_sources.py
+++ b/tests/test_image_sources.py
@@ -607,5 +607,36 @@ def test_labelme_read(self):
             self.assertEqual(shapes[1].flags, {"hard": False})
 
 
+class TestEarthViewKey(unittest.TestCase):
+    """How EarthView finds its API key (no network access needed)."""
+
+    def _earthview(self, env: dict[str, str], **kwargs):
+        from machinevisiontoolbox import EarthView
+
+        clean = {
+            k: v
+            for k, v in os.environ.items()
+            if k not in ("GOOGLE_MAPS_API_KEY", "GOOGLE_API_KEY")
+        }
+        with patch.dict(os.environ, {**clean, **env}, clear=True):
+            return EarthView(**kwargs)
+
+    def test_maps_key_preferred(self):
+        ev = self._earthview({"GOOGLE_MAPS_API_KEY": "maps", "GOOGLE_API_KEY": "other"})
+        self.assertEqual(ev.key, "maps")
+
+    def test_google_api_key_fallback(self):
+        ev = self._earthview({"GOOGLE_API_KEY": "legacy"})
+        self.assertEqual(ev.key, "legacy")
+
+    def test_explicit_key_wins(self):
+        ev = self._earthview({"GOOGLE_MAPS_API_KEY": "maps"}, key="explicit")
+        self.assertEqual(ev.key, "explicit")
+
+    def test_no_key(self):
+        ev = self._earthview({})
+        self.assertIsNone(ev.key)
+
+
 if __name__ == "__main__":
     unittest.main()