Eclipses and Pinhole Sundials
Posted on Friday 24 October 2003
Pinhole sundials are just the sort of wonderful devices that one
might find in a cathedral built during the Renaissance.
The sundial works by
focussing the sun's rays into a bright spot on the church's floor. The
movement of this spot marks the course of the day.
The interesting
aspect here is that the shape of the spot is not simply due to the shape
of the hole that it passes through. The hole is so small that it actually acts like a
lens and what is displayed is really an inverted image of the
sun itself. It works just like a giant pinhole camera.
This becomes more apparent when the spot is observed during a solar
eclipse...
|
|
|
