My thoughts

Forums General Discussion Definitions… My thoughts

David Basey


FWIW, here are my thoughts/answers.

  1.  An eclipse is a shadow related phenomenon where one body is cut off from its primary light source by a third. So in a solar eclipse the Sun is hidden by the passage of the Moon’s shadow. The same principle applies to lunar eclipses and eclipses of Jupiter’s satellites by either Jupiter or each other. Occultations refer to bodies passing in front of each other where one is not illuminated by the other. Occultations of stars by the moon or asteroids for example.
  2.  I would suggest the background object has to be absolutely larger. Were it smaller then this would be an occultation.
  3. An example where the foreground object can be absolutely larger might be found in mutual occultations of Jupiter’s satellites. Consider an occultation of Io by Ganymede for example.

There is one other question to consider, when does a transit become an eclipse? After all, in November there is a transit of Mercury not a solar eclipse by Mercury!