Thursday, July 05, 2012

"Measuring the eccentricity of the Earth orbit with a nail and a piece of plywood"

It is in my nature that I get attracted to things like this. When I saw the title of this paper, I can't help but look into it.

Abstract:  I describe how to obtain a rather good experimental determination of the eccentricity of the Earth orbit, as well as the obliquity of the Earth rotation axis, by measuring, over the course of a year, the elevation of the Sun as a function of time during a day. With a very simple "instrument" consisting of an elementary sundial, first-year students can carry out an appealing measurement programme, learn important concepts in experimental physics, see concrete applications of kinematics and changes of reference frames, and benefit from a hands-on introduction to astronomy. 

The journal reference is Eur. J. Phys. 33, 1167 (2012).

My first impression was that this is a primitive "sundial", and the use of "similar triangles" concepts to plot the shadow of the nail over the period of a year.

This isn't a bad exercise at all, and in fact, could easily be given not just to "first-year students", but also to high-school physics students.


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