diff --git a/changelog.d/1243-starfield-sky.md b/changelog.d/1243-starfield-sky.md
index 7d4557672..d3ecbaf95 100644
--- a/changelog.d/1243-starfield-sky.md
+++ b/changelog.d/1243-starfield-sky.md
@@ -2,4 +2,4 @@
   Yale Bright Star Catalogue, drawn as sharp points at their catalogue
   positions for the scene clock, over a soft Milky Way built from ESO/S.
   Brunier's panorama (CC BY 4.0). The Sun and Moon stay, the anime style fades
-  the Milky Way out, and the new assets weigh 319 kB (gekh, #1243).
+  the Milky Way out, and the new assets weigh 296 kB (gekh, #1243).
diff --git a/scripts/build-milky-way.mjs b/scripts/build-milky-way.mjs
index 5e5d3d253..e0703f882 100644
--- a/scripts/build-milky-way.mjs
+++ b/scripts/build-milky-way.mjs
@@ -23,7 +23,8 @@
  *      sit where today's sky has nothing and are far brighter than any star.
  *   4. Blur with a three-pass box approximation of a Gaussian, σ = BLUR_DEG on
  *      the sky: rows wrap in longitude and widen by 1/cos(latitude) so the
- *      blur stays round towards the poles.
+ *      blur stays round towards the poles. Faint glow blends to a second,
+ *      FAINT_BLUR_DEG blur, so it carries no clumps of unresolved stars.
  *   5. Resample into six FACE_SIZE² cube faces in the standard WebGL face
  *      orientation (the renderer uploads them without flipY), with the ICRF
  *      axes as the cube axes — +X to the March equinox, +Z to the north
@@ -43,6 +44,12 @@ import { fileURLToPath } from 'node:url';
 
 export const FACE_SIZE = 1024;
 export const BLUR_DEG = 0.4;
+// Faint glow takes a much wider blur: there the panorama is grain of
+// unresolved stars, which a 0.4° blur leaves as clumps. Bright parts keep the
+// fine blur and their dust lanes; FAINT_RANGE (fraction of black-to-white)
+// is where the two blend.
+export const FAINT_BLUR_DEG = 2;
+const FAINT_RANGE = [0.005, 0.08];
 const WORK_WIDTH = 4096;
 const OPEN_RADIUS = 3;
 const WEBP_QUALITY = 96;
@@ -300,6 +307,26 @@ export function softBlack(x, knee = SOFT_KNEE) {
   return x <= 0 ? 0 : (x * x) / (x + knee);
 }
 
+export function smoothstep(edge0, edge1, x) {
+  const t = Math.min(Math.max((x - edge0) / (edge1 - edge0), 0), 1);
+  return t * t * (3 - 2 * t);
+}
+
+/**
+ * Per pixel, keep `fine` where `weight(luminance of coarse)` is 1 and take
+ * `coarse` where it is 0, blending in between. The weight follows the coarse
+ * copy, so it is smooth itself and draws no seams along dark lanes. Writes
+ * into `fine`.
+ */
+function blendByBrightness(fine, coarse, weight) {
+  const [r] = fine;
+  for (let i = 0; i < r.length; i++) {
+    const w = weight((coarse[0][i] + coarse[1][i] + coarse[2][i]) / 3);
+    for (let c = 0; c < 3; c++)
+      fine[c][i] = coarse[c][i] + (fine[c][i] - coarse[c][i]) * w;
+  }
+}
+
 /** Value at `fraction` of the sorted luminance. */
 function luminancePercentile(planes, fraction) {
   const [r, g, b] = planes;
@@ -342,9 +369,19 @@ async function main() {
   // After the opening: it sinks the starry sky to the dark gaps between
   // stars, and a fill taken before it would stay brighter than the sky.
   for (const planet of PLANETS) paintOut(planes, width, height, planet);
+  const wide = planes.map((plane) => Float32Array.from(plane));
   for (const plane of planes) blurPlane(plane, width, height, sigmaPx);
+  for (const plane of wide)
+    blurPlane(plane, width, height, (FAINT_BLUR_DEG / 180) * height);
   const black = luminancePercentile(planes, BLACK_PERCENTILE);
   const white = luminancePercentile(planes, WHITE_PERCENTILE);
+  blendByBrightness(planes, wide, (luminance) =>
+    smoothstep(
+      FAINT_RANGE[0],
+      FAINT_RANGE[1],
+      (luminance - black) / (white - black),
+    ),
+  );
   let total = 0;
   for (const face of CUBE_FACES) {
     const pixels = Buffer.alloc(FACE_SIZE * FACE_SIZE * 3);
diff --git a/src/data/local_data/sky/README.md b/src/data/local_data/sky/README.md
index 175542da5..e20b1fb77 100644
--- a/src/data/local_data/sky/README.md
+++ b/src/data/local_data/sky/README.md
@@ -8,7 +8,7 @@ whole-globe view and show compression blocks.
 | File | Content | Size |
 | ---- | ------- | ---- |
 | `bright_stars.json` | 9,096 stars: J2000 RA/Dec, V magnitude, B−V | 235 KB |
-| `milkyway_{px,nx,py,ny,pz,nz}.webp` | Milky Way glow, six 1024² cube faces, no stars | 85 KB |
+| `milkyway_{px,nx,py,ny,pz,nz}.webp` | Milky Way glow, six 1024² cube faces, no stars | 62 KB |
 
 ## Stars — Yale Bright Star Catalogue
 
@@ -44,7 +44,8 @@ Centre.
 **Changes made** (CC BY 4.0 asks for them to be stated): resampled to
 4096×2048, stars removed with a 7×7 morphological opening, two planets
 (Jupiter, by position) painted over with the median of the surrounding sky,
-blurred (σ = 0.4°), reprojected from galactic coordinates to ICRF cube faces,
+blurred (σ = 0.4°, blending to σ = 2° in the faint glow so unresolved
+stars leave no clumps), reprojected from galactic coordinates to ICRF cube faces,
 black level set at the median sky with a soft knee (the faint glow away
 from the galactic plane fades to black), gamma-encoded and saved as
 WebP. Build:
diff --git a/src/data/local_data/sky/milkyway_nx.webp b/src/data/local_data/sky/milkyway_nx.webp
index 9c75115c5..fb14fb996 100644
Binary files a/src/data/local_data/sky/milkyway_nx.webp and b/src/data/local_data/sky/milkyway_nx.webp differ
diff --git a/src/data/local_data/sky/milkyway_ny.webp b/src/data/local_data/sky/milkyway_ny.webp
index a85f3d47e..fb0a48760 100644
Binary files a/src/data/local_data/sky/milkyway_ny.webp and b/src/data/local_data/sky/milkyway_ny.webp differ
diff --git a/src/data/local_data/sky/milkyway_nz.webp b/src/data/local_data/sky/milkyway_nz.webp
index 154e0454f..002e483dc 100644
Binary files a/src/data/local_data/sky/milkyway_nz.webp and b/src/data/local_data/sky/milkyway_nz.webp differ
diff --git a/src/data/local_data/sky/milkyway_px.webp b/src/data/local_data/sky/milkyway_px.webp
index 2bbb49174..e14e3aded 100644
Binary files a/src/data/local_data/sky/milkyway_px.webp and b/src/data/local_data/sky/milkyway_px.webp differ
diff --git a/src/data/local_data/sky/milkyway_py.webp b/src/data/local_data/sky/milkyway_py.webp
index 779353c64..194331c55 100644
Binary files a/src/data/local_data/sky/milkyway_py.webp and b/src/data/local_data/sky/milkyway_py.webp differ
diff --git a/src/data/local_data/sky/milkyway_pz.webp b/src/data/local_data/sky/milkyway_pz.webp
index 50f0793a6..06624bf21 100644
Binary files a/src/data/local_data/sky/milkyway_pz.webp and b/src/data/local_data/sky/milkyway_pz.webp differ
diff --git a/src/tooling/skyAssets.test.mjs b/src/tooling/skyAssets.test.mjs
index 5c666e87d..75e0ad063 100644
--- a/src/tooling/skyAssets.test.mjs
+++ b/src/tooling/skyAssets.test.mjs
@@ -9,6 +9,7 @@ import {
   cubeFaceDirection,
   directionToPlateCarree,
   icrfToGalactic,
+  smoothstep,
   softBlack,
 } from '../../scripts/build-milky-way.mjs';
 import { raDecToUnitVector } from '../sky/stars.js';
@@ -121,3 +122,11 @@ test('the black level eases in instead of cutting the faint sky into contours',
   assert.ok(softBlack(0.003) < 0.0003);
   close(softBlack(1), 1 - 0.03, 1e-3);
 });
+
+test('the faint-glow blend weight eases between its edges', () => {
+  assert.equal(smoothstep(0.1, 0.2, 0), 0);
+  assert.equal(smoothstep(0.1, 0.2, 0.1), 0);
+  close(smoothstep(0.1, 0.2, 0.15), 0.5, 1e-9);
+  assert.equal(smoothstep(0.1, 0.2, 0.2), 1);
+  assert.equal(smoothstep(0.1, 0.2, 9), 1);
+});