bug: add missing Sun in VOUnits simple units

astropy/units/format/vounit.py

@@ -43,7 +43,7 @@ def _generate_unit_names():
             "solRad", "sr", "T", "u", "V", "voxel", "W", "Wb", "yr",
         ]  # fmt: skip
         binary_bases = ["bit", "byte", "B"]
-        simple_units = ["Angstrom", "angstrom", "AU", "au", "Ba", "dB", "mas"]
+        simple_units = ["Angstrom", "angstrom", "AU", "au", "Ba", "dB", "mas", "Sun"]
         si_prefixes = [
             "y", "z", "a", "f", "p", "n", "u", "m", "c", "d",
             "", "da", "h", "k", "M", "G", "T", "P", "E", "Z", "Y"

astropy/units/tests/test_format.py

@@ -681,6 +681,15 @@ def test_vounit_details():
     assert u.Unit("ka", format="vounit") == u.Unit("1000 yr")
     assert u.Unit("pix", format="vounit") == u.Unit("pixel", format="vounit")
 
+    # Regression test for astropy/astroquery#2480
+    assert u.Unit("Sun", format="vounit") is u.Sun
+
+    # Test that adding a prefix to a simple units raises a warning
+    with pytest.warns(
+        UnitsWarning, match="Unit 'kdB' not supported by the VOUnit standard.*"
+    ):
+        u.Unit("kdB", format="vounit")
+
     # The da- prefix is not allowed, and the d- prefix is discouraged
     assert u.dam.to_string("vounit") == "10m"
     assert u.Unit("dam dag").to_string("vounit") == "100g.m"

docs/changes/units/15832.bugfix.rst

@@ -0,0 +1 @@
+Fix a missing ``Sun`` unit in the list of VOUnits simple_units.