diff --git a/plugin/contents/ui/dancer.html b/plugin/contents/ui/dancer.html
index 19032c3..daa52fd 100644
--- a/plugin/contents/ui/dancer.html
+++ b/plugin/contents/ui/dancer.html
@@ -1470,20 +1470,35 @@ function constellationArtTransform(source, target) {
                    .map(v => v / source.length);
   const qc = target.reduce((p, v) => [p[0] + v.x, p[1] + v.y], [0, 0])
                    .map(v => v / target.length);
-  let dot = 0, cross = 0, energy = 0;
+  let dot = 0, cross = 0, mirrorA = 0, mirrorB = 0, energy = 0;
   for (let i = 0; i < source.length; i++) {
     const px = source[i][0] - pc[0], py = source[i][1] - pc[1];
     const qx = target[i].x - qc[0], qy = target[i].y - qc[1];
     dot += px * qx + py * qy;
     cross += px * qy - py * qx;
+    mirrorA += px * qx - py * qy;
+    mirrorB += py * qx + px * qy;
     energy += px * px + py * py;
   }
   if (energy < 1e-6) return null;
-  const a = dot / energy;
-  const b = cross / energy;
-  const e = qc[0] - a * pc[0] + b * pc[1];
-  const f = qc[1] - b * pc[0] - a * pc[1];
-  return [a, b, -b, a, e, f];
+  const candidate = (a, b, c, d) => {
+    const e = qc[0] - a * pc[0] - c * pc[1];
+    const f = qc[1] - b * pc[0] - d * pc[1];
+    const matrix = [a, b, c, d, e, f];
+    const error = source.reduce((sum, p, i) => {
+      const dx = a * p[0] + c * p[1] + e - target[i].x;
+      const dy = b * p[0] + d * p[1] + f - target[i].y;
+      return sum + dx * dx + dy * dy;
+    }, 0);
+    return { matrix, error };
+  };
+  const rotate = candidate(dot / energy, cross / energy,
+                           -cross / energy, dot / energy);
+  /* Ao observar a esfera por dentro, várias cartas precisam inverter a
+     orientação leste/oeste. Esta alternativa inclui a reflexão sem shear. */
+  const reflect = candidate(mirrorA / energy, mirrorB / energy,
+                            mirrorB / energy, -mirrorA / energy);
+  return (reflect.error < rotate.error ? reflect : rotate).matrix;
 }
 
 function drawConstellationArt(c, constellation, lst, W, horizonPx, previewProjector) {