Sundials, Paths, and Eclipses

The sundial has always amazed me and I've never quite understood them. Its stunning to think that people were able to develop these instruments such a long time ago. The information that was totally new to me involved shadow sticks. It would seem like they would work, but people were able to realize that they weren't. This was due to the fact that the sun's position changed based on the time of the year, so they weren't reliable. To combat that, the sundial was made to "have a gnomon which points to the celestial pole" and the "gnomon's upper edge is parallel to the rotation axis of the Earth." This allowed the sundial to be reliable at any point of the year, unlike the shadow stick.



I also never knew about solar time verse clock time. I knew that sundials were not totally correct, but didn't know the reason why. I knew that the earth's speed around the sun wasn't constant, but I didn't put two and two together to realize the error of solar time. The earth rotates faster in January because "the Earth is closer to the Sun in January than July so its orbital speed is higher." We try to keep everything constant, so "the equation of time converts this to local mean time – based on the imaginary mean Sun that moves eastwards along the ecliptic at a constant rate." It really is amazing to know that people were able to realize this, and shows just how far we have come. From shadow sticks, to sundials, to clocks. The progression has come such a long way and is so precise nowadays.

Eclipses are amazing natural occurrences, especially the total eclipses due to their rarity. I would love to be able to see one in my life, but I'll cross that bridge at another point. What I found interesting was that they are so rare, but also that there are different types of eclipses. To be able to see a total eclipse is almost magical because of its rarity, and also because of its small window of opportunity. It only occurs for a small area, and only for a few minutes, but during that time it must be amazing. I found it pretty cool how they have already predicted were the eclipses will occur for many years to come. When I read that the only thing I could think about is that if one of them is incorrect, and what the ensuing uproar would be like.