diff --git a/src/pg_rad/objects.py b/src/pg_rad/objects.py
index 9e544c8..39ab185 100644
--- a/src/pg_rad/objects.py
+++ b/src/pg_rad/objects.py
@@ -1,8 +1,6 @@
 import math
 from typing import Self
 
-from pg_rad.isotope import Isotope
-
 class Object:
     def __init__(
             self,
@@ -32,45 +30,4 @@ class Object:
         return math.dist(
             (self.x, self.y, self.z),
             (other.x, other.y, other.z),
-        )
-    
-class Source(Object):
-    _id_counter = 1
-    def __init__(
-            self,
-            x: float,
-            y: float,
-            z: float,
-            activity: int,
-            isotope: Isotope,
-            name: str | None = None,
-            color: str = "red"):
-        """A point source.
-
-        Args:
-            x (float): X coordinate.
-            y (float): Y coordinate.
-            z (float): Z coordinate.
-            activity (int): Activity A in MBq.
-            isotope (Isotope): The isotope.
-            name (str | None, optional): Can give the source a unique name.
-            Defaults to None, making the name sequential.
-            (Source-1, Source-2, etc.).
-            color (str, optional): Matplotlib compatible color string. Defaults to "red".
-        """
-        
-        self.id = Source._id_counter
-        Source._id_counter += 1
-
-        # default name derived from ID if not provided
-        if name is None:
-            name = f"Source {self.id}"
-
-        super().__init__(x, y, z, name, color)
-
-        self.activity = activity
-        self.isotope = isotope
-        self.color = color
-
-    def __repr__(self):
-        return f"Source(name={self.name}, pos={(self.x, self.y, self.z)}, isotope={self.isotope.name}, A={self.activity} MBq)"
\ No newline at end of file
+        )
\ No newline at end of file
diff --git a/src/pg_rad/sources.py b/src/pg_rad/sources.py
new file mode 100644
index 0000000..9c85353
--- /dev/null
+++ b/src/pg_rad/sources.py
@@ -0,0 +1,43 @@
+from pg_rad.objects import Object
+from pg_rad.isotope import Isotope
+
+class PointSource(Object):
+    _id_counter = 1
+    def __init__(
+            self,
+            x: float,
+            y: float,
+            z: float,
+            activity: int,
+            isotope: Isotope,
+            name: str | None = None,
+            color: str = "red"):
+        """A point source.
+
+        Args:
+            x (float): X coordinate.
+            y (float): Y coordinate.
+            z (float): Z coordinate.
+            activity (int): Activity A in MBq.
+            isotope (Isotope): The isotope.
+            name (str | None, optional): Can give the source a unique name.
+            Defaults to None, making the name sequential.
+            (Source-1, Source-2, etc.).
+            color (str, optional): Matplotlib compatible color string. Defaults to "red".
+        """
+        
+        self.id = PointSource._id_counter
+        PointSource._id_counter += 1
+
+        # default name derived from ID if not provided
+        if name is None:
+            name = f"Source {self.id}"
+
+        super().__init__(x, y, z, name, color)
+
+        self.activity = activity
+        self.isotope = isotope
+        self.color = color
+
+    def __repr__(self):
+        return f"PointSource(name={self.name}, pos={(self.x, self.y, self.z)}, isotope={self.isotope.name}, A={self.activity} MBq)"
\ No newline at end of file