LIT Angular radius is arcsin(r/d). These two balls are built so r/d is the same number, so the angles match. The check uses the camera position as the eye.
AMBER Equal angular size is why a nearer smaller body can match a farther larger one. The sun and the moon are the famous case. This page does not use their measured radii.
MODEL Gold is far and large. Silver is near and small. From this seat they match.
MATCHER starts the near sphere at the wrong radius and tries others. The gauger keeps a try only when the angular-size error drops. Gold stays put. The page throws if MATCHER does not improve.
Checking the sphere.
Seal sha256(name|slug|blurb): 41e4bdfd7c21db673ab7495086e91db6b09dc9304edbf774fba447cb7aae0cb0