diff --git a/src/app/features/body-detail/body-detail.model.ts b/src/app/features/body-detail/body-detail.model.ts
index eed591b..65d9462 100644
--- a/src/app/features/body-detail/body-detail.model.ts
+++ b/src/app/features/body-detail/body-detail.model.ts
@@ -26,8 +26,8 @@ export interface BodyDetailViewModel {
   /**
    * What this world is inferred to look like, and the quantities that inference rests on. Always
    * present — every body has measurements enough to place it somewhere — but its individual
-   * fields are nullable, since a body whose host star is not in the catalogue has no derived
-   * temperature.
+   * fields are nullable, since a body whose host star's luminosity or whose orbit's size is not
+   * known has no derived temperature.
    */
   appearance: PlanetAppearance;
   /** True when a real photograph is being shown rather than the derived surface. */
diff --git a/src/app/features/body-detail/body-readouts.ts b/src/app/features/body-detail/body-readouts.ts
index 67611fc..ef09264 100644
--- a/src/app/features/body-detail/body-readouts.ts
+++ b/src/app/features/body-detail/body-readouts.ts
@@ -71,12 +71,18 @@ export function bodyReadouts(body: BodyDetailViewModel): BodyReadouts {
 /**
  * The derived surface is a reasoned illustration, and a panel of real measurements sitting next
  * to it is exactly the context in which it could be mistaken for another one.
+ *
+ * With no temperature, it says what is missing without claiming which: the host's luminosity, or
+ * the orbit's size. It used to say the host was not in the catalogue, which is so for 27 of the
+ * 2 714 planets it was printed on. Of the rest, 2 420 have no semi-major axis, and since 869635b
+ * 267 have a host no survey measured the brightness of — OGLE-2005-BLG-390L b, read inside its
+ * own host's system.
  */
 function provenanceFor(body: BodyDetailViewModel): string {
   if (body.hasPhotography) {
     return 'Surface: NASA/ESA/USGS photography.';
   }
   return body.appearance.equilibriumTemperatureK === null
-    ? 'Surface illustrated from this body’s measured size and mass. Its host star is not in the catalogue, so no temperature could be derived. Not an observation — no image of this world exists.'
+    ? 'Surface illustrated from this body’s measured size and mass. No temperature could be derived: its star’s luminosity or its orbit’s size is not known. Not an observation — no image of this world exists.'
     : 'Surface illustrated from the measurements above — size, density and the temperature derived from its star’s output and its orbit. Not an observation — no image of this world exists.';
 }
diff --git a/src/app/features/galaxy-system/system-object-card.component.spec.ts b/src/app/features/galaxy-system/system-object-card.component.spec.ts
index ff59b0d..4c0bd50 100644
--- a/src/app/features/galaxy-system/system-object-card.component.spec.ts
+++ b/src/app/features/galaxy-system/system-object-card.component.spec.ts
@@ -108,7 +108,9 @@ describe('SystemObjectCardComponent', () => {
       appearance: appearance({ equilibriumTemperatureK: null }),
     });
     expect(block(host, 'Derived')).not.toContain('Equilibrium temp.');
-    expect(host.textContent).toContain('host star is not in the catalogue');
+    // Not that the host is missing, which it is for 27 of the 2 714 planets without a temperature.
+    expect(host.textContent).toContain('its star’s luminosity or its orbit’s size is not known');
+    expect(host.textContent).not.toContain('not in the catalogue');
   });
 
   it('emits rather than navigating, so the scene decides what selection means', () => {