diff --git a/.oxfmtrc.json b/.oxfmtrc.json
index ec1ba3f..e72fba9 100644
--- a/.oxfmtrc.json
+++ b/.oxfmtrc.json
@@ -9,6 +9,7 @@
     "**/*.css",
     "**/*.md",
     "**/*.yaml",
-    "pnpm-lock.yaml"
+    "pnpm-lock.yaml",
+    "apps/site/public/star-names.json"
   ]
 }
diff --git a/apps/site/public/star-names.json b/apps/site/public/star-names.json
new file mode 100644
index 0000000..c725a2f
--- /dev/null
+++ b/apps/site/public/star-names.json
@@ -0,0 +1 @@
+[[1,"Alpheratz","Andromeda"],[2,"Caph","Cassiopeia"],[11,"Algenib","Pegasus"],[25,"Ankaa","Phoenix"],[43,"Fulu","Cassiopeia"],[50,"Schedar","Cassiopeia"],[56,"Diphda","Cetus"],[67,"Achird","Cassiopeia"],[82,"Castula","Cassiopeia"],[104,"Mirach","Andromeda"],[105,"Wurren","Phoenix"],[111,"Revati","Pisces"],[120,"Adhil","Andromeda"],[123,"Ruchbah","Cassiopeia"],[129,"Polaris","Ursa Minor"],[134,"Alpherg","Pisces"],[138,"Titawin","Andromeda"],[140,"Nembus","Andromeda"],[142,"Achernar","Eridanus"],[152,"Torcular","Pisces"],[158,"Baten Kaitos","Cetus"],[159,"Segin","Cassiopeia"],[161,"Mothallah","Triangulum"],[163,"Mesarthim","Aries"],[166,"Sheratan","Aries"],[186,"Alrescha","Pisces"],[189,"Almach","Andromeda"],[194,"Hamal","Aries"],[210,"Mira","Cetus"],[250,"Kaffaljidhma","Cetus"],[257,"Lilii Borea","Aries"],[258,"Miram","Perseus"],[261,"Bharani","Aries"],[267,"Angetenar","Eridanus"],[275,"Azha","Eridanus"],[287,"Acamar","Eridanus"],[290,"Menkar","Cetus"],[300,"Algol","Perseus"],[302,"Misam","Perseus"],[304,"Botein","Aries"],[307,"Dalim","Fornax"],[311,"Zibal","Eridanus"],[328,"Mirfak","Perseus"],[344,"Ran","Eridanus"],[354,"Atik","Perseus"],[357,"Rana","Eridanus"],[359,"Celaeno","Taurus"],[360,"Electra","Taurus"],[362,"Taygeta","Taurus"],[365,"Maia","Taurus"],[368,"Merope","Taurus"],[370,"Alcyone","Taurus"],[376,"Atlas","Taurus"],[377,"Pleione","Taurus"],[395,"Menkib","Perseus"],[397,"Zaurak","Eridanus"],[420,"Beid","Eridanus"],[433,"Keid","Eridanus"],[445,"Prima Hyadum","Taurus"],[454,"Secunda Hyadum","Taurus"],[463,"Beemim","Eridanus"],[468,"Ain","Taurus"],[470,"Chamukuy","Taurus"],[482,"Aldebaran","Taurus"],[485,"Theemin","Eridanus"],[495,"Sceptrum","Eridanus"],[515,"Tabit","Orion"],[529,"Hassaleh","Auriga"],[535,"Almaaz","Auriga"],[538,"Saclateni","Auriga"],[547,"Haedus","Auriga"],[558,"Cursa","Eridanus"],[574,"Capella","Auriga"],[576,"Rigel","Orion"],[605,"Bellatrix","Orion"],[606,"Elnath","Taurus"],[614,"Nihal","Lepus"],[622,"Mintaka","Orion"],[627,"Arneb","Lepus"],[633,"Meissa","Orion"],[638,"Hatysa","Orion"],[640,"Alnilam","Orion"],[642,"Tianguan","Taurus"],[652,"Alnitak","Orion"],[656,"Phact","Columba"],[669,"Saiph","Orion"],[683,"Wazn","Columba"],[688,"Betelgeuse","Orion"],[695,"Menkalinan","Auriga"],[699,"Mahasim","Auriga"],[723,"Elkurud","Columba"],[734,"Propus","Gemini"],[753,"Furud","Canis Major"],[754,"Tejat","Gemini"],[757,"Mirzam","Canis Major"],[761,"Canopus","Carina"],[784,"Alhena","Gemini"],[798,"Mebsuta","Gemini"],[803,"Alzirr","Gemini"],[806,"Sirius","Canis Major"],[843,"Adhara","Canis Major"],[847,"Nganurganity","Canis Major"],[850,"Mekbuda","Gemini"],[853,"Muliphein","Canis Major"],[862,"Wezen","Canis Major"],[892,"Wasat","Gemini"],[915,"Aludra","Canis Major"],[918,"Gomeisa","Canis Minor"],[936,"Castor","Gemini"],[943,"Jishui","Gemini"],[947,"Procyon","Canis Minor"],[960,"Pollux","Gemini"],[980,"Azmidi","Puppis"],[1015,"Naos","Puppis"],[1021,"Tureis","Puppis"],[1040,"Tarf","Cancer"],[1044,"Alsciaukat","Lynx"],[1051,"Avior","Carina"],[1056,"Muscida","Ursa Major"],[1074,"Minchir","Hydra"],[1089,"Asellus Borealis","Cancer"],[1096,"Asellus Australis","Cancer"],[1102,"Ashlesha","Hydra"],[1104,"Alsephina","Vela"],[1127,"Talitha","Ursa Major"],[1129,"Acubens","Cancer"],[1137,"Alkaphrah","Ursa Major"],[1151,"Nahn","Cancer"],[1153,"Suhail","Vela"],[1173,"Miaplacidus","Carina"],[1179,"Aspidiske","Carina"],[1190,"Markeb","Vela"],[1191,"Intercrus","Ursa Major"],[1192,"Alphard","Hydra"],[1204,"Alterf","Leo"],[1231,"Ukdah","Hydra"],[1233,"Subra","Leo"],[1251,"Zhang","Hydra"],[1252,"Rasalas","Leo"],[1257,"Felis","Hydra"],[1271,"Regulus","Leo"],[1280,"Adhafera","Leo"],[1281,"Tania Borealis","Ursa Major"],[1288,"Algieba","Leo"],[1292,"Tania Australis","Ursa Major"],[1358,"Praecipua","Leo Minor"],[1367,"Chalawan","Ursa Major"],[1369,"Alkes","Crater"],[1374,"Merak","Ursa Major"],[1377,"Dubhe","Ursa Major"],[1393,"Zosma","Leo"],[1394,"Chertan","Leo"],[1400,"Alula Australis","Ursa Major"],[1401,"Alula Borealis","Ursa Major"],[1421,"Giausar","Draco"],[1451,"Taiyangshou","Ursa Major"],[1462,"Denebola","Leo"],[1465,"Zavijava","Virgo"],[1469,"Phecda","Ursa Major"],[1489,"Alchiba","Corvus"],[1496,"Imai","Crux"],[1497,"Megrez","Ursa Major"],[1498,"Gienah","Corvus"],[1507,"Zaniah","Virgo"],[1513,"Ginan","Crux"],[1522,"Acrux","Crux"],[1533,"Algorab","Corvus"],[1535,"Gacrux","Crux"],[1543,"Chara","Canes Venatici"],[1544,"Kraz","Corvus"],[1559,"Porrima","Virgo"],[1567,"La Superba","Canes Venatici"],[1571,"Mimosa","Crux"],[1572,"Tianyi","Draco"],[1584,"Alioth","Ursa Major"],[1587,"Minelauva","Virgo"],[1589,"Cor Caroli","Canes Venatici"],[1590,"Taiyi","Draco"],[1596,"Vindemiatrix","Virgo"],[1605,"Diadem","Coma Berenices"],[1633,"Mizar","Ursa Major"],[1635,"Spica","Virgo"],[1637,"Alcor","Ursa Major"],[1648,"Heze","Virgo"],[1668,"Alkaid","Ursa Major"],[1681,"Muphrid","Boötes"],[1691,"Hadar","Centaurus"],[1694,"Menkent","Centaurus"],[1696,"Thuban","Draco"],[1705,"Kang","Virgo"],[1713,"Syrma","Virgo"],[1715,"Arcturus","Boötes"],[1718,"Xuange","Boötes"],[1721,"Khambalia","Virgo"],[1739,"Elgafar","Virgo"],[1746,"Seginus","Boötes"],[1751,"Rigil Kentaurus","Centaurus"],[1752,"Toliman","Centaurus"],[1771,"Izar","Boötes"],[1778,"Zubenelgenubi","Libra"],[1790,"Kochab","Ursa Minor"],[1801,"Nekkar","Boötes"],[1802,"Brachium","Libra"],[1828,"Zubeneschamali","Libra"],[1846,"Alkalurops","Boötes"],[1847,"Pherkad","Ursa Minor"],[1852,"Edasich","Draco"],[1854,"Nusakan","Corona Borealis"],[1866,"Zubenelhakrabi","Libra"],[1869,"Alphecca","Corona Borealis"],[1890,"Unukalhai","Serpens"],[1894,"Gudja","Serpens"],[1917,"Iklil","Scorpius"],[1924,"Fang","Scorpius"],[1927,"Dschubba","Scorpius"],[1943,"Acrab","Scorpius"],[1950,"Marsic","Hercules"],[1959,"Jabbah","Scorpius"],[1968,"Yed Prior","Ophiuchus"],[1974,"Yed Posterior","Ophiuchus"],[1979,"Alniyat","Scorpius"],[1997,"Cujam","Hercules"],[2004,"Athebyne","Draco"],[2005,"Antares","Scorpius"],[2013,"Kornephoros","Hercules"],[2014,"Marfik","Ophiuchus"],[2022,"Paikauhale","Scorpius"],[2032,"Atria","Triangulum Australe"],[2040,"Larawag","Scorpius"],[2043,"Xamidimura","Scorpius"],[2045,"Pipirima","Scorpius"],[2072,"Sabik","Ophiuchus"],[2076,"Aldhibah","Draco"],[2078,"Guniibuu","Ophiuchus"],[2079,"Rasalgethi","Hercules"],[2081,"Sarin","Hercules"],[2113,"Lesath","Scorpius"],[2117,"Maasym","Hercules"],[2118,"Shaula","Scorpius"],[2119,"Rastaban","Draco"],[2123,"Sargas","Scorpius"],[2126,"Rasalhague","Ophiuchus"],[2136,"Cervantes","Ara"],[2140,"Cebalrai","Ophiuchus"],[2146,"Fuyue","Scorpius"],[2148,"Dziban","Draco"],[2157,"Grumium","Draco"],[2164,"Eltanin","Draco"],[2181,"Alnasl","Sagittarius"],[2192,"Yildun","Ursa Minor"],[2198,"Polis","Sagittarius"],[2211,"Kaus Media","Sagittarius"],[2221,"Kaus Australis","Sagittarius"],[2232,"Kaus Borealis","Sagittarius"],[2245,"Fafnir","Draco"],[2260,"Vega","Lyra"],[2286,"Sheliak","Lyra"],[2289,"Ainalrami","Sagittarius"],[2293,"Nunki","Sagittarius"],[2303,"Alya","Serpens"],[2315,"Sulafat","Lyra"],[2321,"Ascella","Sagittarius"],[2333,"Polaris Australis","Octans"],[2335,"Okab","Aquila"],[2340,"Meridiana","Corona Australis"],[2344,"Albaldah","Sagittarius"],[2351,"Aladfar","Lyra"],[2355,"Altais","Draco"],[2365,"Arkab Prior","Sagittarius"],[2368,"Arkab Posterior","Sagittarius"],[2369,"Rukbat","Sagittarius"],[2381,"Anser","Vulpecula"],[2383,"Albireo","Cygnus"],[2398,"Alsafi","Draco"],[2403,"Sham","Sagitta"],[2415,"Tarazed","Aquila"],[2416,"Fawaris","Cygnus"],[2423,"Altair","Aquila"],[2435,"Libertas","Aquila"],[2436,"Terebellum","Sagittarius"],[2437,"Alshain","Aquila"],[2489,"Algedi","Capricornus"],[2494,"Alshat","Capricornus"],[2495,"Dabih","Capricornus"],[2496,"Peacock","Pavo"],[2498,"Sadr","Cygnus"],[2509,"Aldulfin","Delphinus"],[2519,"Rotanev","Delphinus"],[2530,"Sualocin","Delphinus"],[2533,"Deneb","Cygnus"],[2544,"Aljanah","Cygnus"],[2545,"Albali","Aquarius"],[2569,"Musica","Delphinus"],[2595,"Kitalpha","Equuleus"],[2603,"Alderamin","Cepheus"],[2622,"Sadalsuud","Aquarius"],[2623,"Alfirk","Cepheus"],[2628,"Bunda","Aquarius"],[2632,"Nashira","Capricornus"],[2640,"Azelfafage","Cygnus"],[2643,"Enif","Pegasus"],[2651,"Deneb Algedi","Capricornus"],[2659,"Aldhanab","Grus"],[2672,"Sadalmelik","Aquarius"],[2674,"Kurhah","Cepheus"],[2677,"Alnair","Grus"],[2685,"Biham","Pegasus"],[2705,"Ancha","Aquarius"],[2712,"Sadachbia","Aquarius"],[2741,"Situla","Aquarius"],[2750,"Homam","Pegasus"],[2751,"Tiaki","Grus"],[2756,"Matar","Pegasus"],[2765,"Sadalbari","Pegasus"],[2774,"Skat","Aquarius"],[2778,"Fomalhaut","Piscis Austrinus"],[2779,"Helvetios","Pegasus"],[2788,"Fumalsamakah","Pisces"],[2790,"Scheat","Pegasus"],[2793,"Markab","Pegasus"],[2824,"Salm","Pegasus"],[2830,"Alkarab","Pegasus"],[2836,"Veritate","Andromeda"],[2848,"Errai","Cepheus"]]
\ No newline at end of file
diff --git a/apps/site/src/components/Aurora.astro b/apps/site/src/components/Aurora.astro
index 2a914bc..ccc8fc2 100644
--- a/apps/site/src/components/Aurora.astro
+++ b/apps/site/src/components/Aurora.astro
@@ -32,6 +32,9 @@ import {
     <path d="M12 11v5.5M12 7.75v.01"></path>
   </svg>
 </button>
+<!-- Names the sun, moon, planet or star under the pointer (or a tap). The
+     popover covers the same for screen readers. -->
+<div class="sky-tip gmt-glass-subtle" aria-hidden="true" hidden></div>
 <div id="sky-info" class="sky-info gmt-glass" popover>
   <div class="sky-sites" role="group" aria-label="Seen from">
     {
@@ -58,8 +61,9 @@ import {
           {coords(site.lat, site.lon)}, eye height {site.eye}&nbsp;m.
         </p>
         <p>
-          The stars, moon and {site.ground} are real and show this moment.
-          The aurora is simulated.
+          It is always night here, but the stars, planets, moon and sun are
+          where they really are right now, above the real {site.ground}. The
+          aurora is simulated.
         </p>
         <dl>
           {site.credits.map(([what, source]) => (
@@ -85,7 +89,11 @@ import {
 </div>
 
 <script>
-  import type { AuroraMessage, WorkerMessage } from "../scripts/aurora.worker";
+  import type {
+    AuroraMessage,
+    SkyLabel,
+    WorkerMessage,
+  } from "../scripts/aurora.worker";
 
   // Order matches what the worker destructures.
   const TOKENS = [
@@ -147,11 +155,16 @@ import {
       );
       worker.onmessage = ({ data }: MessageEvent<WorkerMessage>) => {
         if (typeof data === "object") {
-          site = data.site;
-          show();
+          if ("pick" in data) {
+            label(data.pick);
+          } else {
+            site = data.site;
+            show();
+          }
           return;
         }
         const on = data === "on";
+        if (!on) label(null);
         canvas.classList.toggle("on", on);
         if (info) info.hidden = !on;
       };
@@ -182,6 +195,60 @@ import {
     }
   }
 
+  // Tooltips: over bare sky the page asks the worker what is drawn under the
+  // pointer (at most once a frame) and names it.
+  const tip = document.querySelector<HTMLElement>(".sky-tip");
+  let over = false;
+  let asked: [number, number, number] | null = null;
+  const bare = (target: EventTarget | null) =>
+    target === document.documentElement ||
+    target === document.body ||
+    (target instanceof HTMLElement && target.tagName === "MAIN");
+  const label = (found: SkyLabel | null) => {
+    if (!tip) return;
+    tip.hidden = !found || !over || !canvas?.classList.contains("on");
+    if (!found || tip.hidden) return;
+    const note = document.createElement("span");
+    note.textContent = found.note;
+    tip.replaceChildren(found.name, ...(found.note ? [note] : []));
+    // Centred on the object, but kept inside the window at the sides.
+    const half = tip.offsetWidth / 2 + 4;
+    const width = document.documentElement.clientWidth;
+    tip.style.left = `${Math.min(Math.max(found.x, half), width - half)}px`;
+    tip.style.top = `${found.y}px`;
+    tip.classList.toggle("below", found.y < 48);
+  };
+  const point = (event: PointerEvent) => {
+    over = bare(event.target);
+    if (!over || !post) return label(null);
+    const reach = event.pointerType === "mouse" ? 12 : 28;
+    if (!asked) {
+      requestAnimationFrame(() => {
+        if (asked && over) {
+          const [x, y, r] = asked;
+          post?.({ type: "pick", x, y, reach: r });
+        }
+        asked = null;
+      });
+    }
+    asked = [event.clientX, event.clientY, reach];
+  };
+  document.addEventListener(
+    "pointermove",
+    (event) => {
+      if (event.pointerType !== "touch") point(event);
+    },
+    { passive: true },
+  );
+  document.addEventListener("pointerdown", point, { passive: true });
+  // A touch pointer "leaves" as the finger lifts, right after the tap that
+  // asked; its label stays until the next tap instead.
+  document.documentElement.addEventListener("pointerleave", (event) => {
+    if (event.pointerType === "touch") return;
+    over = false;
+    label(null);
+  });
+
   // Switching site: fade the sky out, swap, and fade back in when the worker
   // reports the new frame is up.
   choices.forEach((button, i) =>
@@ -189,6 +256,7 @@ import {
       if (i === site) return;
       site = i;
       show();
+      label(null);
       if (!post || !canvas) return;
       canvas.classList.add("quick");
       canvas.classList.remove("on");
@@ -257,6 +325,29 @@ import {
     opacity: 1;
   }
 
+  .sky-tip {
+    position: fixed;
+    z-index: 4;
+    padding: 0.15rem 0.5rem;
+    color: var(--gmt-ice);
+    font-size: var(--gmt-text-xs);
+    white-space: nowrap;
+    pointer-events: none;
+    translate: -50% calc(-100% - 12px);
+  }
+  .sky-tip :global(span) {
+    color: var(--gmt-ice-dim);
+  }
+  .sky-tip :global(span)::before {
+    content: " · ";
+  }
+  .sky-tip.below {
+    translate: -50% 12px;
+  }
+  .sky-tip[hidden] {
+    display: none;
+  }
+
   .sky-info {
     position: fixed;
     inset: auto 12px 52px auto;
@@ -291,7 +382,7 @@ import {
   }
   .sky-info dl {
     display: grid;
-    grid-template-columns: 4.5rem 1fr;
+    grid-template-columns: 5.5rem 1fr;
     gap: 0.25rem 0.75rem;
     margin: 0 0 0.5rem;
   }
diff --git a/apps/site/src/scripts/aurora.shaders.ts b/apps/site/src/scripts/aurora.shaders.ts
index 70cfccd..e8c7b55 100644
--- a/apps/site/src/scripts/aurora.shaders.ts
+++ b/apps/site/src/scripts/aurora.shaders.ts
@@ -117,6 +117,9 @@ uniform vec2 uTan;
 uniform float uPxAng;
 uniform vec4 uMoon;       // direction, angular radius
 uniform vec3 uMoonN, uSun;
+uniform vec2 uSunDisc;    // angular radius, fraction not behind the moon
+uniform vec3 uShadow;     // earth's shadow axis from the moon's centre, moon radii
+uniform vec2 uShadowR;    // umbra and penumbra radii, moon radii
 uniform float uMoonlight;
 uniform float uGlow;      // city light near the horizon, 0..1
 uniform float uLights;    // lit windows and streets, 0..1
@@ -150,9 +153,28 @@ float fetchCoarse(float x, float k) {
 float profile(float h, float g) {
   return smoothstep(94.0, 106.0, h) * exp(-max(h - 106.0, 0.0) / (25.0 + 45.0 * g));
 }
+// Earth's shadow on the moon: how far the surface point n (moon radii from
+// its centre) is from the shadow's axis, and the sunlight left there
+// (0 in the umbra, 1 outside the penumbra).
+float shadowDist(vec3 n) {
+  vec3 q = n - uShadow;
+  return length(q - uSun * dot(q, uSun));
+}
+float sunlit(vec3 n) {
+  return smoothstep(uShadowR.x, uShadowR.y, shadowDist(n));
+}
 vec3 moon(vec3 rd) {
+  if (uMoon.y < -0.02) return vec3(0.0);
   float cm = dot(rd, uMoon.xyz);
-  if (cm < cos(uMoon.w * 3.0) || uMoon.y < -0.02) return vec3(0.0);
+  // Daylight washes the moon out: half as bright while the sun is up, so the
+  // sun always outshines it.
+  float washed = 1.0 - 0.5 * smoothstep(-0.0145, 0.03, uSun.y);
+  // The same soft glow as the sun's, as strong as the moon is full and lit.
+  float full = (0.5 - 0.5 * dot(uSun, uMoon.xyz)) * sunlit(-uMoon.xyz);
+  float a = acos(clamp(cm, -1.0, 1.0));
+  vec3 glow = full * (mix(uIce, uCyan, 0.3) * 0.3 * exp(-a / 0.012)
+    + mix(uIce, uCyan, 0.6) * 0.035 * exp(-a / 0.08));
+  if (cm < cos(uMoon.w * 3.0)) return glow * washed;
   vec3 o = (rd - uMoon.xyz * cm) / sin(uMoon.w);
   float r = length(o);
   float px = uPxAng / uMoon.w;
@@ -164,12 +186,76 @@ vec3 moon(vec3 rd) {
   float lon = atan(dot(n, west), dot(n, -uMoon.xyz));
   float alb = texture2D(uMoonTex, vec2(0.5 + lon / (2.0 * PI), 0.5 - lat / PI)).r;
   float day = max(dot(n, uSun), 0.0);
-  float halo = exp(-(1.0 - cm) / (uMoon.w * uMoon.w * 6.0)) * 0.06;
-  float full = 0.5 - 0.5 * dot(uSun, uMoon.xyz);
-  return uIce * (cover * alb * (2.2 * day + 0.03) + halo * full);
+  // Lunar eclipse: the penumbra dims softly; in the umbra only sunlight bent
+  // through the earth's air reaches the moon, a dim glow brightening toward
+  // the edge (copper in life, the theme's purple here) with a turquoise
+  // fringe at the edge, from ozone.
+  float lit = sunlit(n);
+  float d = shadowDist(n);
+  float edge = (d - uShadowR.x) / 0.12;
+  vec3 bent = uPurple * (0.07 + 0.2 * smoothstep(0.0, uShadowR.x, d))
+    + uCyan * 0.1 * exp(-edge * edge);
+  vec3 surface = alb * (uIce * (2.2 * day * lit + 0.03) + 2.2 * day * (1.0 - lit) * bent);
+  // Less glow over the disc itself, so the maria still show.
+  return (surface * cover + glow * (1.0 - 0.8 * cover)) * washed;
+}
+// The sun, only while it is really up: an ice-blue disc at true size, a faint
+// 22° ice halo and, when low, a sun pillar. The moon can eclipse it. The sky stays dark (always night here).
+// Halo colours run in the theme's order where real ones run red to blue.
+const float HALO = 0.3840;  // 22° halo radius
+vec3 sun(vec3 rd) {
+  float up = smoothstep(-0.0145, 0.03, uSun.y);
+  if (up <= 0.0) return vec3(0.0);
+  float cs = dot(rd, uSun);
+  float a = acos(clamp(cs, -1.0, 1.0));
+  float px = uPxAng / uSunDisc.x;
+  float r = a / uSunDisc.x;
+  // Solar eclipse: the moon's dark disc in front. What is left of the sun
+  // still glows (the last sliver flares: the diamond ring).
+  float mr = acos(clamp(dot(rd, uMoon.xyz), -1.0, 1.0)) / uMoon.w;
+  float mpx = uPxAng / uMoon.w;
+  float behind = 1.0 - smoothstep(1.0 - mpx, 1.0 + mpx, mr);
+  float shine = sqrt(uSunDisc.y);
+  // Limb-darkened disc and a tight aureole of forward scattering.
+  float disc = (1.0 - smoothstep(1.0 - px, 1.0 + px, r))
+    * (0.55 + 0.45 * sqrt(max(0.0, 1.0 - r * r))) * (1.0 - behind);
+  vec3 ice = mix(uIce, uCyan, 0.3);
+  vec3 col = ice * (2.4 * disc + 0.35 * shine * exp(-a / 0.012))
+    + mix(uIce, uCyan, 0.6) * 0.04 * shine * exp(-a / 0.08);
+  // Totality: the corona, pearly and streaked, two or three solar radii out.
+  float total = 1.0 - smoothstep(0.0, 0.004, uSunDisc.y);
+  if (total > 0.0) {
+    vec3 side = normalize(cross(uSun, vec3(0.0, 1.0, 0.0)));
+    vec3 lift = cross(side, uSun);
+    vec2 pa = normalize(vec2(dot(rd, side), dot(rd, lift)) + 1e-6);
+    float streak = noise(pa * 3.0 + 5.0) * noise(pa * 9.0 + 11.0);
+    float h = max(r - 1.0, 0.0);
+    float corona = 0.6 * exp(-h / 0.3) + 0.5 * streak * exp(-h / 1.5);
+    col += mix(uIce, uCyan, 0.2) * corona * total * (1.0 - behind) * step(1.0, r);
+  }
+  // Thin cirrus or diamond dust: the crystals come and go across the sky,
+  // so the halos are patchy and drift slowly.
+  vec2 q = vec2(atan(rd.x, rd.z) * 5.0, rd.y * 9.0) + uT * vec2(0.004, 0.002);
+  float veil = smoothstep(0.15, 0.8, 0.65 * noise(q) + 0.35 * noise(q * 2.7 + 9.0));
+  // 22° halo: a faint ring, coloured on its inner side and broken where the
+  // crystals thin out. Soft on both sides: a sharp inner edge with a long
+  // outer fade makes the sky inside look darker (the Cornsweet effect).
+  float dh = a - HALO;
+  float ring = exp(-dh * dh / (dh < 0.0 ? 0.00008 : 0.00018));
+  vec3 tint = mix(uPurple, mix(uCyan, uIce, smoothstep(0.004, 0.03, dh)),
+    smoothstep(-0.004, 0.012, dh));
+  col += tint * ring * 0.035 * veil * veil * uSunDisc.y;
+  // A sun pillar over a low sun, from plate crystals.
+  float se = uSun.y, ce = sqrt(1.0 - se * se);
+  float dAz = atan(rd.x * uSun.z - rd.z * uSun.x, rd.x * uSun.x + rd.z * uSun.z);
+  float dAlt = asin(clamp(rd.y, -1.0, 1.0)) - asin(se);
+  float low = 1.0 - smoothstep(0.03, 0.11, se);
+  col += ice * 0.25 * low * uSunDisc.y * exp(-dAz * dAz * ce * ce / 0.000016)
+    * exp(-abs(dAlt) / 0.05);
+  return col * up;
 }
 // Sky seen along rd (above the horizon): background, city glow, moonlight,
-// the aurora and the moon. Before tone mapping. j is the step jitter.
+// the aurora, the moon and the sun. Before tone mapping. j is the step jitter.
 vec3 skyColour(vec3 rd, float j) {
   float c2 = dot(rd.xz, rd.xz);
   vec3 acc = vec3(0.0);
@@ -205,7 +291,7 @@ vec3 skyColour(vec3 rd, float j) {
   vec3 col = uVoid + uTeal * 0.05 * exp(-e * 8.0)
     + uGlow * (uTeal * 0.09 * exp(-e * 9.0) + uIce * 0.035 * exp(-e * 22.0))
     + uMoonlight * (uIce * 0.02 + uTeal * 0.05) * (0.5 + 0.5 * exp(-e * 3.0));
-  return col + (acc * 0.035 + moon(rd)) * air;
+  return col + (acc * 0.035 + moon(rd) + sun(rd)) * air;
 }
 // City lights along the shore, by azimuth bin: on or off, and how bright.
 float shoreLight(float az) {
@@ -287,7 +373,8 @@ void main() {
 
 // Catalogue stars: J2000 directions turned into the sky of date. Fainter
 // near the horizon (extinction) and when the moon brightens the sky. They
-// twinkle; they never move except with the sky itself.
+// twinkle; they never move except with the sky itself. The planets use the
+// same program, barely twinkling.
 export const STAR_VS = `
 precision highp float;
 ${PROJECT}
@@ -296,6 +383,8 @@ attribute vec2 aMag;
 uniform mat3 uStars;
 uniform vec3 uIce, uCyan;
 uniform float uPx, uT, uLimit, uFade;
+// 1 for planets, which hardly twinkle.
+uniform float uSteady;
 varying vec3 vCol;
 void main() {
   vec3 w = uStars * aDir;
@@ -304,7 +393,7 @@ void main() {
   float b = pow(2.512, -m);
   float a = min(2.6 * sqrt(b), 1.6) * smoothstep(uLimit + 0.3, uLimit - 0.6, m) * uFade;
   float seed = fract(sin(dot(aDir.xy, vec2(91.7, 37.3)) + aDir.z * 11.1) * 4375.85);
-  float amp = 0.1 + 0.3 * (1.0 - smoothstep(0.05, 0.5, alt));
+  float amp = (0.1 + 0.3 * (1.0 - smoothstep(0.05, 0.5, alt))) * (1.0 - 0.8 * uSteady);
   float tw = 1.0 + amp * sin(uT * (1.1 + 2.0 * seed) + seed * 60.0)
     * sin(uT * 0.37 + seed * 17.0);
   vCol = mix(uIce, uCyan, 0.35 * smoothstep(0.4, -0.1, aMag.y)) * a * tw;
diff --git a/apps/site/src/scripts/aurora.sites.ts b/apps/site/src/scripts/aurora.sites.ts
index e807317..73023b3 100644
--- a/apps/site/src/scripts/aurora.sites.ts
+++ b/apps/site/src/scripts/aurora.sites.ts
@@ -102,8 +102,8 @@ export const SITES: Site[] = [
     dip: 74,
     decl: 11,
     curtains: [
-      { base: 550, centre: -250, half: 1000 },
-      { base: 900, centre: -400, half: 1600 },
+      { base: 750, centre: -350, half: 1300 },
+      { base: 1000, centre: -470, half: 1800 },
     ],
     glow: 1,
     limit: 4.2,
@@ -120,6 +120,11 @@ export const SITES: Site[] = [
 export const SKY_CREDITS: [string, string][] = [
   ["Stars", "Yale Bright Star Catalogue, 5th revised edition (CDS V/50)."],
   ["Moon", "NASA's Scientific Visualization Studio."],
+  [
+    "Planets",
+    "JPL Keplerian elements for approximate positions (E. M. Standish).",
+  ],
+  ["Star names", "IAU Catalog of Star Names (IAU WGSN)."],
 ];
 
 const POINTS = [
diff --git a/apps/site/src/scripts/aurora.sky.ts b/apps/site/src/scripts/aurora.sky.ts
index 17015e8..c6508d7 100644
--- a/apps/site/src/scripts/aurora.sky.ts
+++ b/apps/site/src/scripts/aurora.sky.ts
@@ -2,7 +2,9 @@
 // precession, and the sun and moon. Vectors use the scene's world frame:
 // x east, y up, z north. Angles in radians unless named *Deg.
 // Moon and sun follow Meeus, "Astronomical Algorithms" (2nd ed.), ch. 25 and
-// 47, with the larger periodic terms only (moon good to about 0.05°).
+// 47, with the full periodic tables (moon good to about 10″, which eclipses
+// need). The planets use JPL's mean Keplerian elements (good to a few arcminutes over
+// 1800–2050) and Meeus ch. 41 for their brightness.
 
 import type { Site } from "./aurora.sites";
 
@@ -23,6 +25,10 @@ const RAD = Math.PI / 180;
 const ARCSEC = RAD / 3600;
 
 const julian = (ms: number) => ms / 86400000 + 2440587.5;
+// Terrestrial time runs ΔT ahead of the clock (UTC): 32.184 s plus 37 leap
+// seconds since 2017. The moon moves half an arcsecond a second, so the
+// orbit formulas need it.
+const DELTA_T = 69.184;
 
 /** Row-major 3×3 product a·b. */
 function mul(a: Mat3, b: Mat3): Mat3 {
@@ -33,7 +39,7 @@ function mul(a: Mat3, b: Mat3): Mat3 {
   }) as Mat3;
 }
 
-function apply(m: Mat3, v: Vec3): Vec3 {
+export function apply(m: Mat3, v: Vec3): Vec3 {
   return [
     m[0] * v[0] + m[1] * v[1] + m[2] * v[2],
     m[3] * v[0] + m[4] * v[1] + m[5] * v[2],
@@ -114,6 +120,34 @@ const MOON_LR: number[][] = [
   [2, -1, -2, 0, 2390, 10056],
   [1, 0, 1, 0, -2348, 6322],
   [2, -2, 0, 0, 2236, -9884],
+  [0, 1, 2, 0, -2120, 5751],
+  [0, 2, 0, 0, -2069, 0],
+  [2, -2, -1, 0, 2048, -4950],
+  [2, 0, 1, -2, -1773, 4130],
+  [2, 0, 0, 2, -1595, 0],
+  [4, -1, -1, 0, 1215, -3958],
+  [0, 0, 2, 2, -1110, 0],
+  [3, 0, -1, 0, -892, 3258],
+  [2, 1, 1, 0, -810, 2616],
+  [4, -1, -2, 0, 759, -1897],
+  [0, 2, -1, 0, -713, -2117],
+  [2, 2, -1, 0, -700, 2354],
+  [2, 1, -2, 0, 691, 0],
+  [2, -1, 0, -2, 596, 0],
+  [4, 0, 1, 0, 549, -1423],
+  [0, 0, 4, 0, 537, -1117],
+  [4, -1, 0, 0, 520, -1571],
+  [1, 0, -2, 0, -487, -1739],
+  [2, 1, 0, -2, -399, 0],
+  [0, 0, 2, -2, -381, -4421],
+  [1, 1, 1, 0, 351, 0],
+  [3, 0, -2, 0, -340, 0],
+  [4, 0, -3, 0, 330, 0],
+  [2, -1, 2, 0, 327, 0],
+  [0, 2, 1, 0, -323, 1165],
+  [1, 1, -1, 0, 299, 0],
+  [2, 0, 3, 0, 294, 0],
+  [2, 0, -1, -2, 0, 8752],
 ];
 // Meeus table 47.B: D, M, M', F, latitude (1e-6°).
 const MOON_B: number[][] = [
@@ -134,6 +168,49 @@ const MOON_B: number[][] = [
   [2, -1, -1, 1, 2463],
   [2, -1, 0, 1, 2211],
   [2, -1, -1, -1, 2065],
+  [0, 1, -1, -1, -1870],
+  [4, 0, -1, -1, 1828],
+  [0, 1, 0, 1, -1794],
+  [0, 0, 0, 3, -1749],
+  [0, 1, -1, 1, -1565],
+  [1, 0, 0, 1, -1491],
+  [0, 1, 1, 1, -1475],
+  [0, 1, 1, -1, -1410],
+  [0, 1, 0, -1, -1344],
+  [1, 0, 0, -1, -1335],
+  [0, 0, 3, 1, 1107],
+  [4, 0, 0, -1, 1021],
+  [4, 0, -1, 1, 833],
+  [0, 0, 1, -3, 777],
+  [4, 0, -2, 1, 671],
+  [2, 0, 0, -3, 607],
+  [2, 0, 2, -1, 596],
+  [2, -1, 1, -1, 491],
+  [2, 0, -2, 1, -451],
+  [0, 0, 3, -1, 439],
+  [2, 0, 2, 1, 422],
+  [2, 0, -3, -1, 421],
+  [2, 1, -1, 1, -366],
+  [2, 1, 0, 1, -351],
+  [4, 0, 0, 1, 331],
+  [2, -1, 1, 1, 315],
+  [2, -2, 0, -1, 302],
+  [0, 0, 1, 3, -283],
+  [2, 1, 1, -1, -229],
+  [1, 1, 0, -1, 223],
+  [1, 1, 0, 1, 223],
+  [0, 1, -2, -1, -220],
+  [2, 1, -1, -1, -220],
+  [1, 0, 1, 1, -185],
+  [2, -1, -2, -1, 181],
+  [0, 1, 2, 1, -177],
+  [4, 0, -2, -1, 176],
+  [4, -1, -1, -1, 166],
+  [1, 0, 1, -1, -164],
+  [4, 0, 1, -1, 132],
+  [1, 0, -1, -1, -119],
+  [4, -1, 0, -1, 115],
+  [2, -2, 0, 1, 107],
 ];
 
 /** Geocentric ecliptic longitude, latitude (radians) and distance (km). */
@@ -172,7 +249,8 @@ export function moonEcliptic(t: number): [number, number, number] {
   return [(Lp + sl / 1e6) * RAD, (sb / 1e6) * RAD, 385000.56 + sr / 1000];
 }
 
-/** Geocentric ecliptic longitude of the sun (radians). */
+/** Apparent geocentric ecliptic longitude of the sun (radians), less the
+ * nutation the moon also leaves out. */
 function sunLongitude(t: number): number {
   const L0 = 280.46646 + 36000.76983 * t;
   const M = (357.52911 + 35999.05029 * t) * RAD;
@@ -180,7 +258,176 @@ function sunLongitude(t: number): number {
     (1.914602 - 0.004817 * t) * Math.sin(M) +
     (0.019993 - 0.000101 * t) * Math.sin(2 * M) +
     0.000289 * Math.sin(3 * M);
-  return (L0 + C) * RAD;
+  // Aberration: the sun appears 20.5″ behind where it is.
+  return (L0 + C - 20.4898 / 3600 + perturbation(t) / 3600) * RAD;
+}
+
+/** The pull of the moon, Venus, Mars and Jupiter on the earth (and the
+ * formula's own drift), in arcseconds of solar longitude. Fitted to VSOP87
+ * via astronomy-engine over 1990–2060: the formula above alone is out by up
+ * to 39″, this leaves 14″ over 1900–2100, which keeps eclipses right. */
+function perturbation(t: number): number {
+  const e = (100.464 + 35999.372 * t) * RAD;
+  const v = e - (181.979 + 58517.815 * t) * RAD;
+  const j = e - (34.396 + 3034.746 * t) * RAD;
+  const ma = e - (-4.553 + 19140.303 * t) * RAD;
+  const d = (297.8501921 + 445267.1114034 * t) * RAD;
+  const m = (357.5291 + 35999.0503 * t) * RAD;
+  const om = (125.04 - 1934.136 * t) * RAD;
+  return (
+    -8.51 +
+    6.46 * Math.sin(d) -
+    4.82 * Math.sin(v) +
+    5.51 * Math.sin(2 * v) +
+    0.64 * Math.sin(3 * v) -
+    7.37 * Math.sin(j) +
+    2.73 * Math.sin(2 * j) -
+    2.12 * Math.sin(2 * ma) -
+    2.1 * Math.sin(om) -
+    0.68 * Math.sin(j - m) -
+    2.53 * Math.cos(j - m) -
+    3.01 * Math.sin(m) -
+    1.19 * Math.cos(m)
+  );
+}
+
+// JPL, "Approximate Positions of the Planets" (E. M. Standish), table 1:
+// a (au), e, I, L, long. perihelion, long. node (degrees) at J2000, then
+// their rates per Julian century. J2000 ecliptic and equinox.
+const ORBITS: Record<string, number[]> = {
+  mercury: [
+    0.38709927, 0.20563593, 7.00497902, 252.2503235, 77.45779628, 48.33076593,
+    0.00000037, 0.00001906, -0.00594749, 149472.67411175, 0.16047689,
+    -0.12534081,
+  ],
+  venus: [
+    0.72333566, 0.00677672, 3.39467605, 181.9790995, 131.60246718, 76.67984255,
+    0.0000039, -0.00004107, -0.0007889, 58517.81538729, 0.00268329, -0.27769418,
+  ],
+  earth: [
+    1.00000261, 0.01671123, -0.00001531, 100.46457166, 102.93768193, 0,
+    0.00000562, -0.00004392, -0.01294668, 35999.37244981, 0.32327364, 0,
+  ],
+  mars: [
+    1.52371034, 0.0933941, 1.84969142, -4.55343205, -23.94362959, 49.55953891,
+    0.00001847, 0.00007882, -0.00813131, 19140.30268499, 0.44441088,
+    -0.29257343,
+  ],
+  jupiter: [
+    5.202887, 0.04838624, 1.30439695, 34.39644051, 14.72847983, 100.47390909,
+    -0.00011607, -0.00013253, -0.00183714, 3034.74612775, 0.21252668,
+    0.20469106,
+  ],
+  saturn: [
+    9.53667594, 0.05386179, 2.48599187, 49.95424423, 92.59887831, 113.66242448,
+    -0.0012506, -0.00050991, 0.00193609, 1222.49362201, -0.41897216,
+    -0.28867794,
+  ],
+};
+
+/** Heliocentric J2000 ecliptic position (au) from ORBITS. */
+function heliocentric(el: number[], t: number): Vec3 {
+  const [a, e, i, l, peri, node] = [0, 1, 2, 3, 4, 5].map(
+    (k) => el[k]! + el[k + 6]! * t,
+  ) as [number, number, number, number, number, number];
+  const m = ((((l - peri) % 360) + 540) % 360) - 180;
+  const w = (peri - node) * RAD;
+  const M = m * RAD;
+  let E = M + e * Math.sin(M);
+  for (let k = 0; k < 6; k++) {
+    E -= (E - e * Math.sin(E) - M) / (1 - e * Math.cos(E));
+  }
+  const xp = a * (Math.cos(E) - e);
+  const yp = a * Math.sqrt(1 - e * e) * Math.sin(E);
+  const [cw, sw] = [Math.cos(w), Math.sin(w)];
+  const [cn, sn] = [Math.cos(node * RAD), Math.sin(node * RAD)];
+  const [ci, si] = [Math.cos(i * RAD), Math.sin(i * RAD)];
+  return [
+    (cw * cn - sw * sn * ci) * xp + (-sw * cn - cw * sn * ci) * yp,
+    (cw * sn + sw * cn * ci) * xp + (-sw * sn + cw * cn * ci) * yp,
+    sw * si * xp + cw * si * yp,
+  ];
+}
+
+// Saturn's north pole (J2000 equatorial), for the tilt of its rings.
+const SATURN_POLE: Vec3 = [0.0855, 0.0732, 0.9936];
+
+/** Apparent magnitude from distances to the sun (r) and earth (d), the
+ * phase angle i (degrees) and, for Saturn, the ring tilt (Meeus 41). */
+const MAGNITUDE: Record<string, (i: number, ring: number) => number> = {
+  mercury: (i) => -0.42 + 0.038 * i - 0.000273 * i * i + 0.000002 * i ** 3,
+  venus: (i) => -4.4 + 0.0009 * i + 0.000239 * i * i - 0.00000065 * i ** 3,
+  mars: (i) => -1.52 + 0.016 * i,
+  jupiter: (i) => -9.4 + 0.005 * i,
+  saturn: (i, ring) =>
+    -8.88 + 0.044 * i - 2.6 * Math.abs(ring) + 1.25 * ring * ring,
+};
+// B − V colour index, as in the star catalogue.
+const COLOUR: Record<string, number> = {
+  mercury: 0.93,
+  venus: 0.82,
+  mars: 1.36,
+  jupiter: 0.83,
+  saturn: 1.04,
+};
+const EPS0 = 23.43928 * RAD;
+
+/** Planet names in the order planets() lists them. */
+export const PLANETS = ["Mercury", "Venus", "Mars", "Jupiter", "Saturn"];
+
+/** The naked-eye planets as star records: J2000 equatorial direction, then
+ * magnitude and colour (see starData in the worker). */
+export function planets(t: number): Float32Array {
+  const earth = heliocentric(ORBITS.earth!, t);
+  const sunDist = Math.hypot(...earth);
+  const names = PLANETS.map((name) => name.toLowerCase());
+  const out = new Float32Array(names.length * 5);
+  names.forEach((name, k) => {
+    const p = heliocentric(ORBITS[name]!, t);
+    const g: Vec3 = [p[0] - earth[0], p[1] - earth[1], p[2] - earth[2]];
+    const r = Math.hypot(...p);
+    const d = Math.hypot(...g);
+    const i =
+      Math.acos(
+        Math.min(
+          1,
+          Math.max(-1, (r * r + d * d - sunDist * sunDist) / (2 * r * d)),
+        ),
+      ) / RAD;
+    const [ce, se] = [Math.cos(EPS0), Math.sin(EPS0)];
+    const eq: Vec3 = [
+      g[0] / d,
+      (ce * g[1] - se * g[2]) / d,
+      (se * g[1] + ce * g[2]) / d,
+    ];
+    const ring = -(
+      eq[0] * SATURN_POLE[0] +
+      eq[1] * SATURN_POLE[1] +
+      eq[2] * SATURN_POLE[2]
+    );
+    const mag = MAGNITUDE[name]!(i, ring) + 5 * Math.log10(r * d);
+    out.set([...eq, mag, COLOUR[name]!], k * 5);
+  });
+  return out;
+}
+
+const smoothstep = (a: number, b: number, x: number) => {
+  const k = Math.min(1, Math.max(0, (x - a) / (b - a)));
+  return k * k * (3 - 2 * k);
+};
+
+/** Fraction of a disc of radius a left uncovered by a disc of radius b whose
+ * centre is d away (small angles, so flat geometry). */
+function uncovered(a: number, b: number, d: number): number {
+  if (d >= a + b) return 1;
+  if (d <= b - a) return 0;
+  if (d <= a - b) return 1 - (b * b) / (a * a);
+  const p = Math.acos((d * d + a * a - b * b) / (2 * d * a));
+  const q = Math.acos((d * d + b * b - a * a) / (2 * d * b));
+  const lens =
+    a * a * (p - Math.sin(p) * Math.cos(p)) +
+    b * b * (q - Math.sin(q) * Math.cos(q));
+  return 1 - lens / (Math.PI * a * a);
 }
 
 const normalize = (v: Vec3): Vec3 => {
@@ -197,13 +444,26 @@ export type Sky = {
   /** Lunar north (ecliptic pole is within 1.5° of it). */
   moonNorth: Vec3;
   sun: Vec3;
-  /** 0..1: how much the moon lights the sky (phase and altitude). */
+  /** Sun's angular radius, and the fraction of its disc the moon leaves
+   * uncovered (1 outside a solar eclipse). */
+  sunRadius: number;
+  sunVisible: number;
+  /** Earth's shadow at the moon, in moon radii: the shadow axis relative to
+   * the moon's centre (world frame), then the umbra and penumbra radii. */
+  shadow: Vec3;
+  umbra: number;
+  penumbra: number;
+  /** 0..1: how much the moon lights the sky (phase, altitude, eclipse). */
   moonlight: number;
+  /** The planets as star records, drawn with the stars matrix. */
+  planets: Float32Array;
 };
 
 export function sky(site: Site, ms: number): Sky {
   const jd = julian(ms);
-  const t = (jd - 2451545) / 36525;
+  // Julian centuries of terrestrial time for the orbits; sidereal time uses
+  // the clock.
+  const t = (jd + DELTA_T / 86400 - 2451545) / 36525;
   const gmst =
     (280.46061837 + 360.98564736629 * (jd - 2451545) + 0.000387933 * t * t) *
     RAD;
@@ -228,17 +488,52 @@ export function sky(site: Site, ms: number): Sky {
   const sun = normalize(apply(hor, ecliptic(sunLongitude(t), 0, eps)));
   const moonNorth = normalize(apply(hor, [0, -Math.sin(eps), Math.cos(eps)]));
 
+  const dot = (a: Vec3, b: Vec3) => a[0] * b[0] + a[1] * b[1] + a[2] * b[2];
+  const moonRadius = Math.asin(1737.4 / range);
+
+  // Solar eclipse: how much of the sun's disc the moon leaves showing.
+  const m = (357.52911 + 35999.05029 * t) * RAD;
+  const au = 1.00014 - 0.01671 * Math.cos(m) - 0.00014 * Math.cos(2 * m);
+  const sunRadius = (959.63 / au) * ARCSEC;
+  const sunVisible = uncovered(
+    sunRadius,
+    moonRadius,
+    Math.acos(Math.min(1, dot(sun, moon))),
+  );
+
+  // Lunar eclipse: Earth's shadow cone where the moon crosses it. The
+  // atmosphere widens the earth by 1/85 (Danjon's rule, as eclipse tables use).
+  const mw = apply(hor, geo);
+  const behind = -dot(mw, sun);
+  const shadow = mw.map((c, i) => (sun[i]! * -behind - c) / 1737.4) as Vec3;
+  const sunKm = au * 149597870.7;
+  // Radii below zero: the moon is on the sun's side, out of the shadow.
+  const earth = 6367.5 * (1 + 1 / 85);
+  const umbra =
+    behind > 0 ? (earth - (behind * (696000 - 6367.5)) / sunKm) / 1737.4 : -2;
+  const penumbra =
+    behind > 0 ? (earth + (behind * (696000 + 6367.5)) / sunKm) / 1737.4 : -1;
+  // Sunlight left at the centre of the moon's face.
+  const q = moon.map((c, i) => -c - shadow[i]!) as Vec3;
+  const off = q.map((c, i) => c - sun[i]! * dot(q, sun)) as Vec3;
+  const sunlit = smoothstep(umbra, penumbra, Math.hypot(...off));
+
   // Illuminated fraction from the sun–moon angle, faded by moon altitude.
-  const lit =
-    (1 - (sun[0] * moon[0] + sun[1] * moon[1] + sun[2] * moon[2])) / 2;
+  const lit = (1 - dot(sun, moon)) / 2;
   const alt = Math.asin(moon[1]) / RAD;
   const up = Math.min(1, Math.max(0, (alt + 2) / 17));
   return {
     stars: mul(hor, precession(t)),
     moon,
-    moonRadius: Math.asin(1737.4 / range),
+    moonRadius,
     moonNorth,
     sun,
-    moonlight: lit ** 1.5 * up * up * (3 - 2 * up),
+    sunRadius,
+    sunVisible,
+    shadow,
+    umbra,
+    penumbra,
+    moonlight: lit ** 1.5 * up * up * (3 - 2 * up) * sunlit,
+    planets: planets(t),
   };
 }
diff --git a/apps/site/src/scripts/aurora.worker.ts b/apps/site/src/scripts/aurora.worker.ts
index c28ee98..a7a6f37 100644
--- a/apps/site/src/scripts/aurora.worker.ts
+++ b/apps/site/src/scripts/aurora.worker.ts
@@ -3,8 +3,10 @@
 // Passes per frame:
 // 1. Footprint: each curtain's ground track and brightness into a small
 //    texture (see aurora.shaders.ts).
-// 2. Sky: a fullscreen march through the aurora in perspective, plus the moon.
-// 3. Stars from the Bright Star Catalogue, then the sparks, added on top.
+// 2. Sky: a fullscreen march through the aurora in perspective, plus the moon
+//    and, when it is up, the sun and its ice halos.
+// 3. Stars from the Bright Star Catalogue and the planets, then the sparks,
+//    added on top.
 // 4. The mountain skyline, drawn last so it hides everything behind it.
 // The page sends the theme token values, sizes and visibility; we answer "on"
 // once a frame is up and "off" if we give up.
@@ -24,7 +26,14 @@ import {
 import { getSystemTimeZone, getUnixNow } from "@northguild/gmt";
 import { MOON } from "./aurora.moon";
 import { SITES } from "./aurora.sites";
-import { columns, sky, type Sky } from "./aurora.sky";
+import {
+  PLANETS,
+  apply,
+  columns,
+  sky,
+  type Sky,
+  type Vec3,
+} from "./aurora.sky";
 import { SKYLINE as HELSINKI } from "./skylines/helsinki";
 import { SKYLINE as ISAFJORDUR } from "./skylines/isafjordur";
 
@@ -34,8 +43,9 @@ const MAX_EDGE = 1280;
 const SPARKS = 4000;
 const RAD = Math.PI / 180;
 
-// Wall-clock epoch milliseconds from Temporal (via gmt): the stars and moon
-// need the real time. Frame timing uses rAF stamps, not the wall clock.
+// Wall-clock epoch milliseconds from Temporal (via gmt): the stars, planets,
+// moon and sun need the real time. Frame timing uses rAF stamps, not the wall
+// clock.
 let wallMs = 0;
 const wall = () => (wallMs = getUnixNow() ?? wallMs);
 
@@ -63,10 +73,21 @@ export type AuroraMessage =
   | { type: "site"; site: number }
   | { type: "size"; width: number; height: number }
   | { type: "still"; still: boolean }
-  | { type: "hidden"; hidden: boolean };
-
-/** To the page: the frame is up ("on"), we gave up ("off"), or the site drawn. */
-export type WorkerMessage = "on" | "off" | { site: number };
+  | { type: "hidden"; hidden: boolean }
+  /** What is drawn near this point (CSS pixels), within reach pixels. */
+  | { type: "pick"; x: number; y: number; reach: number };
+
+/** The sun, moon, a planet or a named star as drawn, in CSS pixels from the
+ * canvas's corner; note is "Planet" or a star's constellation. */
+export type SkyLabel = { name: string; note: string; x: number; y: number };
+
+/** To the page: the frame is up ("on"), we gave up ("off"), the site drawn,
+ * or the answer to a pick (for the tooltips). */
+export type WorkerMessage =
+  | "on"
+  | "off"
+  | { site: number }
+  | { pick: SkyLabel | null };
 
 const scope = self as unknown as {
   onmessage: ((event: MessageEvent<AuroraMessage>) => void) | null;
@@ -272,6 +293,7 @@ function start(init: Extract<AuroraMessage, { type: "init" }>): void {
   const seeds = buffer(Float32Array.from({ length: SPARKS * 4 }, Math.random));
   const ridgeBuf = gl.createBuffer();
   let ridgeCount = 0;
+  const planetBuf = gl.createBuffer();
   let starBuf: WebGLBuffer | null = null;
   let starCount = 0;
   let starsAt = 0;
@@ -308,6 +330,8 @@ function start(init: Extract<AuroraMessage, { type: "init" }>): void {
   // Everything that depends on where the viewer stands.
   let site = SITES[0]!;
   let tilt = [0, 0];
+  // Ridge elevation by azimuth (degrees), radians; what is below it is hidden.
+  let ridgeAt = (_az: number) => -Math.PI / 2;
   let cam = new Float32Array(9);
   let tanY = 1;
   // Camera basis as columns (right, up, forward), heading from north. On a
@@ -347,6 +371,13 @@ function start(init: Extract<AuroraMessage, { type: "init" }>): void {
     aim();
     const skyline = SKYLINES[site.id];
     const mesh = skyline ? ridgeMesh(skyline) : new Float32Array(0);
+    if (skyline) {
+      const elev = new Int16Array(bytes(skyline.elev).buffer);
+      ridgeAt = (az) =>
+        ((elev[Math.round((az - skyline.from) / skyline.step)] ?? -9000) /
+          100) *
+        RAD;
+    }
     gl.bindBuffer(gl.ARRAY_BUFFER, ridgeBuf);
     gl.bufferData(gl.ARRAY_BUFFER, mesh, gl.STATIC_DRAW);
     ridgeCount = mesh.length / 4;
@@ -370,6 +401,7 @@ function start(init: Extract<AuroraMessage, { type: "init" }>): void {
   let tuning = true;
   let skyAt = wall();
   let now: Sky = sky(site, skyAt);
+  let planetsAt = 0;
 
   const resize = () => {
     const w = width || 1;
@@ -381,6 +413,55 @@ function start(init: Extract<AuroraMessage, { type: "init" }>): void {
     aim();
   };
 
+  // What the page's pointer is over: the nearest sun, moon, planet or named
+  // star within reach that is up, clear of the skyline, bright enough to be
+  // drawn and in frame.
+  let starDirs: Float32Array | null = null;
+  let named: [number, string, string][] = [];
+  const pick = (px: number, py: number, reach: number): SkyLabel | null => {
+    const w = width || 1;
+    const h = height || 1;
+    const limit = site.limit - 2 * now.moonlight;
+    let best: SkyLabel | null = null;
+    let nearest = reach * reach;
+    const consider = (name: string, note: string, d: Vec3, above: number) => {
+      const alt = Math.asin(d[1]);
+      if (alt < above || alt < ridgeAt(Math.atan2(d[0], d[2]) / RAD)) return;
+      const z = d[0] * cam[6]! + d[1] * cam[7]! + d[2] * cam[8]!;
+      if (z <= 0) return;
+      const nx =
+        (d[0] * cam[0]! + d[1] * cam[1]! + d[2] * cam[2]!) /
+        (z * tanY * (w / h));
+      const ny =
+        (d[0] * cam[3]! + d[1] * cam[4]! + d[2] * cam[5]!) / (z * tanY);
+      if (Math.abs(nx) > 1 || Math.abs(ny) > 1) return;
+      const x = ((nx + 1) / 2) * w;
+      const y = ((1 - ny) / 2) * h;
+      const dist = (x - px) ** 2 + (y - py) ** 2;
+      if (dist >= nearest) return;
+      nearest = dist;
+      best = { name, note, x: Math.round(x), y: Math.round(y) };
+    };
+    // Fainter near the horizon, as the star shader draws it.
+    const seen = (mag: number, d: Vec3) =>
+      mag + 0.12 * (1 / (Math.max(d[1], 0) + 0.04) - 1) < limit;
+    consider("Sun", "", now.sun, -0.83 * RAD);
+    consider("Moon", "", now.moon, 0);
+    const p = now.planets;
+    PLANETS.forEach((name, k) => {
+      const d = apply(now.stars, [p[k * 5]!, p[k * 5 + 1]!, p[k * 5 + 2]!]);
+      if (seen(p[k * 5 + 3]!, d)) consider(name, "Planet", d, 0);
+    });
+    const s = starDirs;
+    if (s) {
+      for (const [i, name, constellation] of named) {
+        const d = apply(now.stars, [s[i * 5]!, s[i * 5 + 1]!, s[i * 5 + 2]!]);
+        if (seen(s[i * 5 + 3]!, d)) consider(name, constellation, d, 0);
+      }
+    }
+    return best;
+  };
+
   const quad = (program: WebGLProgram) => {
     const a = attrib(program, "aPos", tri, 2);
     gl.drawArrays(gl.TRIANGLES, 0, 3);
@@ -392,6 +473,12 @@ function start(init: Extract<AuroraMessage, { type: "init" }>): void {
     if (wall() - skyAt > 1000) {
       skyAt = wallMs;
       now = sky(site, skyAt);
+      planetsAt = 0;
+    }
+    if (!planetsAt) {
+      planetsAt = skyAt;
+      gl.bindBuffer(gl.ARRAY_BUFFER, planetBuf);
+      gl.bufferData(gl.ARRAY_BUFFER, now.planets, gl.DYNAMIC_DRAW);
     }
     const tan = [tanY * (canvas.width / canvas.height), tanY];
     const px = Math.max(1, canvas.height / 540);
@@ -430,25 +517,40 @@ function start(init: Extract<AuroraMessage, { type: "init" }>): void {
     gl.uniform4f(at(sp, "uMoon"), ...now.moon, now.moonRadius);
     gl.uniform3fv(at(sp, "uMoonN"), now.moonNorth);
     gl.uniform3fv(at(sp, "uSun"), now.sun);
+    gl.uniform2f(at(sp, "uSunDisc"), now.sunRadius, now.sunVisible);
+    gl.uniform3fv(at(sp, "uShadow"), now.shadow);
+    gl.uniform2f(at(sp, "uShadowR"), now.umbra, now.penumbra);
     quad(sp);
 
     // 3. Stars and sparks, added on top.
     gl.enable(gl.BLEND);
     gl.blendFunc(gl.ONE, gl.ONE);
+    view(stars);
+    gl.uniformMatrix3fv(at(stars, "uStars"), false, columns(now.stars));
+    gl.uniform1f(at(stars, "uLimit"), site.limit - 2 * now.moonlight);
+    const points = (
+      buf: WebGLBuffer | null,
+      count: number,
+      fade: number,
+      steady: number,
+    ) => {
+      gl.uniform1f(at(stars, "uFade"), fade);
+      gl.uniform1f(at(stars, "uSteady"), steady);
+      const a = attrib(stars, "aDir", buf, 3, 20, 0);
+      const b = attrib(stars, "aMag", buf, 2, 20, 12);
+      gl.drawArrays(gl.POINTS, 0, count);
+      gl.disableVertexAttribArray(a);
+      gl.disableVertexAttribArray(b);
+    };
     if (starBuf && starCount) {
-      view(stars);
-      gl.uniformMatrix3fv(at(stars, "uStars"), false, columns(now.stars));
-      gl.uniform1f(at(stars, "uLimit"), site.limit - 2 * now.moonlight);
-      gl.uniform1f(
-        at(stars, "uFade"),
+      points(
+        starBuf,
+        starCount,
         Math.min(1, (performance.now() - starsAt) / 1500),
+        0,
       );
-      const a = attrib(stars, "aDir", starBuf, 3, 20, 0);
-      const b = attrib(stars, "aMag", starBuf, 2, 20, 12);
-      gl.drawArrays(gl.POINTS, 0, starCount);
-      gl.disableVertexAttribArray(a);
-      gl.disableVertexAttribArray(b);
     }
+    points(planetBuf, now.planets.length / 5, 1, 1);
     view(sparks);
     const s = attrib(sparks, "aSeed", seeds, 4);
     gl.drawArrays(gl.POINTS, 0, sparkCount);
@@ -522,18 +624,22 @@ function start(init: Extract<AuroraMessage, { type: "init" }>): void {
   scope.postMessage("on");
   run();
 
-  // Stars arrive after the first frame so they never delay it. Without them
-  // the aurora still runs.
+  // Stars arrive after the first frame so they never delay it, then the star
+  // names for the tooltips. Without them the aurora still runs.
   fetch(new URL("/stars.bin", self.location.origin))
     .then((res) => (res.ok ? res.arrayBuffer() : Promise.reject(res.status)))
     .then((buf) => {
       if (level > 2) return;
       const data = starData(buf);
+      starDirs = data;
       starBuf = buffer(data);
       starCount = data.length / 5;
       starsAt = still ? -Infinity : performance.now();
       if (!raf) draw();
+      return fetch(new URL("/star-names.json", self.location.origin));
     })
+    .then((res) => (res?.ok ? res.json() : []))
+    .then((list: [number, string, string][]) => (named = list))
     .catch(() => {});
 
   scope.onmessage = ({ data }) => {
@@ -542,6 +648,7 @@ function start(init: Extract<AuroraMessage, { type: "init" }>): void {
       place(data.site);
       skyAt = wall();
       now = sky(site, skyAt);
+      planetsAt = 0;
       draw();
       scope.postMessage("on");
     } else if (data.type === "size") {
@@ -558,6 +665,8 @@ function start(init: Extract<AuroraMessage, { type: "init" }>): void {
       hidden = data.hidden;
       if (hidden) stop();
       else run();
+    } else if (data.type === "pick") {
+      scope.postMessage({ pick: pick(data.x, data.y, data.reach) });
     }
   };
 }
diff --git a/scripts/build-stars.mjs b/scripts/build-stars.mjs
index 5dc3794..279e9b3 100644
--- a/scripts/build-stars.mjs
+++ b/scripts/build-stars.mjs
@@ -6,13 +6,22 @@
 // Run: node scripts/build-stars.mjs
 // Record, 6 bytes little-endian: ra uint16 (0..65536 = 0..360°),
 // dec int16 (±32767 = ±90°), vmag uint8 ((V + 2) × 20), b-v int8 (× 50).
+//
+// Also builds apps/site/public/star-names.json for the sky's tooltips: the
+// IAU Catalog of Star Names (WGSN), matched by HR number, as
+// [record index, name, constellation] for each named star kept above.
 
 import { writeFileSync } from "node:fs";
 import { gunzipSync } from "node:zlib";
 
 const SOURCE = "http://tdc-www.harvard.edu/catalogs/bsc5.dat.gz";
 const LIMIT = 5.5;
+const NAMES = "https://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt";
 const OUT = new URL("../apps/site/public/stars.bin", import.meta.url);
+const NAMES_OUT = new URL(
+  "../apps/site/public/star-names.json",
+  import.meta.url,
+);
 
 const res = await fetch(SOURCE);
 if (!res.ok) throw new Error(`catalogue: HTTP ${res.status}`);
@@ -24,6 +33,8 @@ const text = gunzipSync(Buffer.from(await res.arrayBuffer())).toString(
 const field = (line, from, to) => line.slice(from - 1, to).trim();
 
 const stars = [];
+/** Record index by HR (Bright Star) number. */
+const byHr = new Map();
 for (const line of text.split("\n")) {
   const raH = field(line, 76, 77);
   const vmag = field(line, 103, 107);
@@ -43,6 +54,7 @@ for (const line of text.split("\n")) {
       Number(field(line, 87, 88)) / 60 +
       Number(field(line, 89, 90)) / 3600);
   const bv = Number(field(line, 110, 114) || "0.6");
+  byHr.set(Number(field(line, 1, 4)), stars.length);
   stars.push({ ra, dec, v, bv });
 }
 
@@ -56,3 +68,121 @@ stars.forEach(({ ra, dec, v, bv }, i) => {
 });
 writeFileSync(OUT, buf);
 console.log(`${stars.length} stars, ${buf.length} bytes`);
+
+// The 88 constellations by IAU abbreviation.
+const CONSTELLATIONS = {
+  And: "Andromeda",
+  Ant: "Antlia",
+  Aps: "Apus",
+  Aqr: "Aquarius",
+  Aql: "Aquila",
+  Ara: "Ara",
+  Ari: "Aries",
+  Aur: "Auriga",
+  Boo: "Boötes",
+  Cae: "Caelum",
+  Cam: "Camelopardalis",
+  Cnc: "Cancer",
+  CVn: "Canes Venatici",
+  CMa: "Canis Major",
+  CMi: "Canis Minor",
+  Cap: "Capricornus",
+  Car: "Carina",
+  Cas: "Cassiopeia",
+  Cen: "Centaurus",
+  Cep: "Cepheus",
+  Cet: "Cetus",
+  Cha: "Chamaeleon",
+  Cir: "Circinus",
+  Col: "Columba",
+  Com: "Coma Berenices",
+  CrA: "Corona Australis",
+  CrB: "Corona Borealis",
+  Crv: "Corvus",
+  Crt: "Crater",
+  Cru: "Crux",
+  Cyg: "Cygnus",
+  Del: "Delphinus",
+  Dor: "Dorado",
+  Dra: "Draco",
+  Equ: "Equuleus",
+  Eri: "Eridanus",
+  For: "Fornax",
+  Gem: "Gemini",
+  Gru: "Grus",
+  Her: "Hercules",
+  Hor: "Horologium",
+  Hya: "Hydra",
+  Hyi: "Hydrus",
+  Ind: "Indus",
+  Lac: "Lacerta",
+  Leo: "Leo",
+  LMi: "Leo Minor",
+  Lep: "Lepus",
+  Lib: "Libra",
+  Lup: "Lupus",
+  Lyn: "Lynx",
+  Lyr: "Lyra",
+  Men: "Mensa",
+  Mic: "Microscopium",
+  Mon: "Monoceros",
+  Mus: "Musca",
+  Nor: "Norma",
+  Oct: "Octans",
+  Oph: "Ophiuchus",
+  Ori: "Orion",
+  Pav: "Pavo",
+  Peg: "Pegasus",
+  Per: "Perseus",
+  Phe: "Phoenix",
+  Pic: "Pictor",
+  Psc: "Pisces",
+  PsA: "Piscis Austrinus",
+  Pup: "Puppis",
+  Pyx: "Pyxis",
+  Ret: "Reticulum",
+  Sge: "Sagitta",
+  Sgr: "Sagittarius",
+  Sco: "Scorpius",
+  Scl: "Sculptor",
+  Sct: "Scutum",
+  Ser: "Serpens",
+  Sex: "Sextans",
+  Tau: "Taurus",
+  Tel: "Telescopium",
+  Tri: "Triangulum",
+  TrA: "Triangulum Australe",
+  Tuc: "Tucana",
+  UMa: "Ursa Major",
+  UMi: "Ursa Minor",
+  Vel: "Vela",
+  Vir: "Virgo",
+  Vol: "Volans",
+  Vul: "Vulpecula",
+};
+
+// Fixed-width columns, located from the header row.
+const namesRes = await fetch(NAMES);
+if (!namesRes.ok) throw new Error(`star names: HTTP ${namesRes.status}`);
+const lines = (await namesRes.text()).split("\n");
+const header = lines.find((l) => l.startsWith("#Name/ASCII")) ?? "";
+const col = (label) => header.indexOf(label);
+const [nameAt, designAt, conAt] = [
+  col("Name/Diacritics"),
+  col("Designation"),
+  col("Con"),
+];
+const names = [];
+for (const line of lines) {
+  if (line.startsWith("#") || line.startsWith("$") || !line.trim()) continue;
+  const hr = /^HR (\d+)/.exec(line.slice(designAt, conAt).trim());
+  const index = hr && byHr.get(Number(hr[1]));
+  if (index === undefined || index === null) continue;
+  const name = line.slice(nameAt, designAt).trim();
+  const con = line.slice(conAt, conAt + 3).trim();
+  names.push([index, name, CONSTELLATIONS[con] ?? con]);
+}
+names.sort((a, b) => a[0] - b[0]);
+const json = JSON.stringify(names);
+writeFileSync(NAMES_OUT, json);
+console.log(`${names.length} star names, ${json.length} bytes`);