rod
~ Elite 1000 Member ~
No this is not engraving, however it is topical. When Kepler predicted it in Renaissance times, and when Halley proposed using it as a way to get the most important missing link of the then state of knowledge about our Solar System, the history of this rare event figures large and important in humankind's quest to determine just how big was our immediate neighbourhood, ie the Solar System?
Very briefly, since the orbit of Venus is inclined at a small angle to the orbit of Earth, the 'Morning Star' usually passes above or below the Sun. This event happens in pairs eight years apart that are separated from each other by 105 or 121 years. The last transit was in 2004 and the next will not happen until 2117. Venus passes between the Sun and Earth, and can be seen as a small but distinct dark shadow in a telescope, which needs to be heavily filtered to reduce the Sun's light. If your eyesight is excellent you may just see it naked eye, but using sun filters.
Why was this important in the 18th century? Well, by observing the transit from places on Earth well separated by thousands of miles, and the time of the pass accurately noted, Euclid's geometry could determine our distance from the Sun, and hence the real size of the Solar System, since Kepler had worked out the ratio of the separation of all the known planets, but not the true distance. This meant doing the math on an extremely slender triangle. Whole books have been written on the history of the Transit, and I will stop here.
Today I was able to observe the Transit with my big Dobsonian telescope, and friends joined in with their instruments, here is a taste of the event:
https://picasaweb.google.com/rodcameron2/VenusTransit#
In this small town, neighbours, from age seven to seventy, passing down the quiet street were attracted by the instruments and welcomed into the yard to take a peek, and, by the way, peaks of baseball hats were turned backwards ( as is the fashion of the young) so as not to bump into the scopes.
Rod
Very briefly, since the orbit of Venus is inclined at a small angle to the orbit of Earth, the 'Morning Star' usually passes above or below the Sun. This event happens in pairs eight years apart that are separated from each other by 105 or 121 years. The last transit was in 2004 and the next will not happen until 2117. Venus passes between the Sun and Earth, and can be seen as a small but distinct dark shadow in a telescope, which needs to be heavily filtered to reduce the Sun's light. If your eyesight is excellent you may just see it naked eye, but using sun filters.
Why was this important in the 18th century? Well, by observing the transit from places on Earth well separated by thousands of miles, and the time of the pass accurately noted, Euclid's geometry could determine our distance from the Sun, and hence the real size of the Solar System, since Kepler had worked out the ratio of the separation of all the known planets, but not the true distance. This meant doing the math on an extremely slender triangle. Whole books have been written on the history of the Transit, and I will stop here.
Today I was able to observe the Transit with my big Dobsonian telescope, and friends joined in with their instruments, here is a taste of the event:
https://picasaweb.google.com/rodcameron2/VenusTransit#
In this small town, neighbours, from age seven to seventy, passing down the quiet street were attracted by the instruments and welcomed into the yard to take a peek, and, by the way, peaks of baseball hats were turned backwards ( as is the fashion of the young) so as not to bump into the scopes.
Rod
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