Amateur Astronomers Association of Princeton (AAAP) Monthly Meeting

Occultations, eclipses, and transits are among the most impressive solar system events we can observe. Once portents of doom or omens of the machinations of deities, these events are vivid illustrations of celestial mechanics. Our ability to predict them accurately signals the attrition of magic into rational thought. Nevertheless, they are magical events. At no other times can we get such a sense of the power associated with the movement of massive objects in our relatively near cosmic neighborhood. In particular, a total solar eclipse is an unforgettable experience as the entire landscape quickly darkens and the sun’s magnificent corona appears for a short time.

These events have also been of deep scientific interest on many occasions. Transits of Venus were formerly used to determine the scale of the solar system. Timings of lunar occultations helped refine long-term estimates of the gradual recession of the moon. Historical records of ancient eclipses were useful in pinning down the gradual slowing of Earth’s rotation due to tidal friction. Studies of the sun’s corona enabled advancements in solar physics. Modern techniques have largely taken over in these areas, but such occasions will always remain of deep human interest.