Fermilab Visitor Center analemmatic sundial - Batavia, IL
Posted by: 
adgorn
N 41° 50.363 W 088° 16.013
16T E 394815 N 4632718
Stand on top to cast your shadow and tell the time, just outside of the Lederman Science Center at the Fermi National Accelerator Laboratory.
Waymark Code: WMCDTT
Location: Illinois, United States
Date Posted: 08/26/2011
Views: 1
An analemmatic sundial consists of two main parts. The first is a platform containing the date marks where the person or gnomon stands to cast the shadow towards the hour marks. YOU are the gnomon in an analemmatic sundial. In contrast to most sundials, the gnomon is not in a single, fixed position but, rather, must be placed in a varying position that depends on the date in order for the sundial to indicate the correct time for that date. Notice in my photos the square plates for each month.
The other part is an ellipse which has marks along it that indicate the hours of time. You can see the number 12 for high noon in my photo.
There are various approaches for designing an analemmatic sundial. Empirical methods can be used by making daily and yearly observations of the shadow of a vertical rod. An ellipse is first laid out at the intended site of the sundial, with the minor axis oriented in the north-south direction. Time marks can be placed on the ellipse at selected times during a day of choice, such as hourly, by noting where the shadow of a vertical rod located on the minor axis intersects the ellipse. A date mark can be placed on the minor axis of the ellipse for that day. Observations over the course of a year will be needed to locate other date marks empirically along the minor axis. This experimental method of construction is protracted over time and tedious. Fortunately, there is a very nice analytical way of doing it. That involves things like cosines, tangents, matrices, polar coordinates, declinations, weird looking graphs, etc. which are thoroughly explained in websites like the following:
http://dls-website.com/documents/Analemmatic_Sundials.htm#_Toc123708629
and
http://plus.maths.org/content/os/issue11/features/sundials/index
It is pretty darn amazing what man has been able to figure out through dedicated observation and computation.
I included the flickr posting below to show what it looks like with a person standing on the sundial.
Here's a google map link so you can see what it looks like from above:
View Larger Map
FYI Scientists at Fermilab carry out research in high-energy physics to answer the questions: What is the universe made of? How does it work? Where did it come from?
The Fermilab grounds require a quick security check at the entrance and are accessible by both car or bike. Then you are free to wander and photograph. Tours are offered at the main building. See http://www.fnal.gov/ for more information.