Test an exoplanet's aphelion in the framing radius and a derived surface's white, and give Earth's old TDB error as 8.6 degrees

Two lines the review found unguarded, each now held by a test that fails without it:

- outermostRadiusAu takes an exoplanet's eccentricity as well as a solar-system body's. c45d916 said
  303 of the 1 190 exoplanet systems have an aphelion past their grid ring, but both tests built the
  system from a BodyRecord. The new case is HD 20782 b (a = 1.3649 AU, e = 0.95), the most eccentric
  of them, whose aphelion is 1.66 times its 1.6 AU ring. Control: feeding eccentricity 0 for
  exoplanets fails "reaches an exoplanet's aphelion too" only (1 failed, 843 passed of 844).
- A derived surface resets its marker to white once painted, as a photograph does. Without it every
  exoplanet, the five Uranian moons, Proteus, Nereid, Hyperion, Eris, Haumea and Makemake would show
  their texture multiplied by the kind's flat colour. "paints them after the system is built, one a
  task" now asserts the exoplanet magenta before and 0xffffff after. Control: deleting
  material.color.set(0xffffff) on that path fails that test only (1 failed, 843 passed).

The AD 1000 Earth test's comment said the IAU W taken at TDB left the drawn face 6.6 degrees off.
6.6 is only the turn ΔT adds (1 572 s at 360.9856 deg/day); it adds to the W's own lead, so the
face is 8.57 degrees off. Measured here by putting Earth back on the IAU W at TDB in the renderer:
"expected -8.565166921766826". The 2.3 degrees the comment gives for the old code is the W at
UT + 69.184 s; at UT itself it is 2.0, and the comment now says both.

cbe4908's table also gave the 2025-06-01 12:00 row as "+0.06 before, -0.003 after". Two reviewers
measured the same Horizons point (1.579501 E) at +0.087 before and +0.0034 after: the row should read
+0.09 and +0.003. The message cannot be changed without rewriting history, so it is restated here.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/app/features/galaxy-system/system-orbits-renderer.spec.ts

@@ -464,6 +464,14 @@ describe('outermostRadiusAu', () => {
     renderer.dispose();
   });
 
+  it('reaches an exoplanet’s aphelion too: HD 20782 b’s, 1.66 times its 1.6 AU ring', () => {
+    // The most eccentric of the 303 exoplanet systems with an orbit past their ring, counted on
+    // exoplanets.json (a = 1.3649 AU, e = 0.95).
+    const renderer = new SystemOrbitsRenderer([], [exoplanet({ id: 'HD 20782 b', name: 'HD 20782 b', orbit: { semiMajorAxisAu: 1.3649, eccentricity: 0.95 } })]);
+    expect(renderer.outermostRadiusAu).toBeCloseTo(1.3649 * 1.95, 9);
+    renderer.dispose();
+  });
+
   it('is the grid’s outer ring where every orbit stays inside it', () => {
     const renderer = new SystemOrbitsRenderer([drawn(30, 0.01)], []);
     expect(renderer.outermostRadiusAu).toBe(35);
@@ -511,13 +519,19 @@ describe('derived surfaces', () => {
   const twoPlanets = (): SystemOrbitsRenderer =>
     new SystemOrbitsRenderer([], [exoplanet({ radiusEarth: 1.1 }), exoplanet({ id: 'TRAPPIST-1 c', name: 'TRAPPIST-1 c', radiusEarth: 1.0 })], undefined, 1);
 
-  it('paints them after the system is built, one a task, so entering a system is not held up', async () => {
+  it('paints them after the system is built, one a task, so entering a system is not held up, and in their own colours', async () => {
+    const colours = (renderer: SystemOrbitsRenderer): number[] =>
+      renderer.members.map((member) => ((member.marker as THREE.Mesh).material as THREE.MeshStandardMaterial).color.getHex());
     const renderer = twoPlanets();
     expect(maps(renderer)).toEqual([null, null]);
+    // Until then each is its kind's flat colour, an exoplanet's magenta.
+    expect(colours(renderer)).toEqual([new THREE.Color(0.85, 0.4, 0.85).getHex(), new THREE.Color(0.85, 0.4, 0.85).getHex()]);
     await nextTask();
     expect(maps(renderer).filter(Boolean)).toHaveLength(1);
     await nextTask();
     expect(maps(renderer).every(Boolean)).toBe(true);
+    // Left magenta, every derived surface would be multiplied by it, its green cut by 60 per cent.
+    expect(colours(renderer)).toEqual([0xffffff, 0xffffff]);
     renderer.dispose();
   });
 
@@ -765,8 +779,9 @@ describe('solar-system bodies against Horizons', () => {
 
   it('turns Earth by the UT the clock names, which is its turning: at AD 1000 the Sun stands over Horizons’ point', () => {
     // Horizons' sub-solar longitude from the Sun (observer quantity 14, TIME_TYPE=UT) on JD 2086455,
-    // 1.0510 E, is Earth as it was 8.454 minutes before. Turned by the IAU's W at UT the drawn face
+    // 1.0510 E, is Earth as it was 8.454 minutes before. Turned by the IAU's W at UT + 69.184 s, as it
-    // was 2.3 degrees off; taken at TDB, 6.6.
+    // was, the drawn face was 2.3 degrees off (2.0 at UT itself); taken at TDB, which turns it ΔT
+    // (6.6 degrees) further the same way, 8.6.
     renderer.update(2086455 - 8.45437443 / 1440);
     expect(apart(facing('earth', new THREE.Vector3()).eastDeg, 1.05101)).toBeLessThan(0.15);
   });