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Friday, October 25, 2013

How Many Acres is That?

Ever want to calculate acreage?  Our lake association's insurance carrier recently wanted to know the acreage of our lake.  I'd heard figures ranging from 19 acres to 35.  Pondering the problem, I was reminded of a cool tool I've used to calculate mileage from Google Maps -- a Google Map Pedometer.  with this tool, I've measured the dirt road around our lake and distances I run or walk on a periodic basis.  If figured there must be something similar for measuring acreage, and sure enough:  the Google Planimeter.  With this tool, I was able to measure Taconic Lake to be 33 acres.

Friday, October 18, 2013

Moon Illusion

I was driving down Route 2 toward Troy at 6:30 a.m. this morning and observing a harvest moon as I came over the crest in Cropseyville.  Why did it appear so large to me? Answer: "moon illusion."  To the naked eye, the moon appears larger when it is near the horizon than it does while higher up in the sky (the zenith moon).  It is described in early Greek and Chinese writings. Aristotle mentions it in 350 BCE.  The most likely reason?  Why oculomotor miropsi/macropsia of course.  Not convinced?  See The representation of perceived angular size in human primary visual cortex.  

Take a look tonight... should be pretty much the same story.

The photo above was not taken by me with my iPhone camera.  If it had been, it would look much smaller.  I used it under the creative commons license from Wikipedia.  If you're interested in moon photography, see How to Photograph the Moon.