Peter Barker

**Spheres and orbs in Copernicus**

**Question 1**: Using an 8.5x11 inch sheets of graph paper and a
compass, draw Copernicus' cosmic scheme to scale using the figures indicated
below. Label the spherical shell -- or orb -- corresponding to each object,
in the correct order. (Ptolemy's figures from Exercise 5 are given for comparison.)

Planet |
Relative Distance |
Ptolemy |
Copernicus |

Earth | greatest | 1.04 | |

least | 0.96 | ||

Jupiter | greatest | 14.4 | 5.46 |

least | 8.8 | 4.98 | |

Mars | greatest | 8.8 | 1.67 |

least | 1.2 | 1.38 | |

Mercury | greatest | 0.2 | 0.49 |

least | 0.06 | 0.3 | |

Saturn | greatest | 20.1 | 9.7 |

least | 14.4 | 8.66 | |

Sun | greatest | 1.2 | |

least | 1.1 | ||

Venus | greatest | 1.1 | 0.76 |

least | 0.2 | 0.68 |

**Question 2**: On the sheet provided, figures 2A and 2B show Ptolemy's
*Almagest* model for the sun and for the moon, with the corresponding
three-dimensional orb models. Figures 2C and 2D show Copernicus's models
for the moon and for an outer planet. What would the corresponding orb
models look like?