GEK1506 Heavenly Mathematics & Cultural Astronomy, Tutorial 6

  1. Suppose two stars, A and B, have the same declination but that the right ascension of B is two hours more than A. Suppose A crosses the meridian at midnight. When does B cross the meridian?
  2. What are the inferior (between us and the Sun) planets?
  3. What are the superior (further from the Sun that us) planets?
  4. What time of the night can you see Venus? What about Mars?
  5. Which direction do the planets usually move? Why do they sometimes retrograde?

Helmer Aslaksen
Department of Mathematics
National University of Singapore