Possible Clues:

• Unknown to mathematicians, supporting awful 9 in astronomical model
• Planetarium
• Mechanical solar-system model
• Planetarium model
• Model in a science class
• Heavenly model going like clockwork -- error strangely unknown
• Model of spheres, or about railway termini
• Clockwork solar system model
• Rory beaten up outside about a heavenly model
• Satyr erroneously holds such a heavenly model the wrong way