GEK1506 Heavenly Mathematics & Cultural Astronomy, Tutorial 7, Solutions

  1. When the Earth is near perihelion, which occurs around January 4, the Earth moves faster. That makes it harder for the Moon to overtake the Sun, and the lunar month become longer.
  2. Almost like a circle.
  3. The Moon-Earth plane is different from the Sun-Earth plane.
  4. The Moon casts a small shadow on the Earth. Few people will be inside the shadow. If the Moon is in the shadow of the Earth, half the people on the Earth will see it.
  5. The Earth makes a big shadow that the Moon must pass through during a lunar eclipse. The Moon makes a small shadow that quickly sweeps across the surface of the Earth.
  6. There would be fewer total eclipses, and more annular eclipses.

Helmer Aslaksen
Department of Mathematics
National University of Singapore
helmer.aslaksen@gmail.com