Geobulletin alpha

News from the Geoblogosphere

New from Snet: Lithologs, a new tool to create lithological/sedimentological logs online..

Blog post recommendation

My Failures in Science - Measuring the Earth Part 2

In response to my failure to measure the Earth before (See post here for background and details) I again attempted to measure the Earth using the length of the shadows during the the days before and after the summer solstice. To recap here is the background:

~2200 years ago, a man named Eratosthenes made a pretty good estimation of the size of the Earth using the length of shadows during the summer solstice at two different locations.

To repeat this experiment there are some requirements:

1. I needed a measuring stick that was perpendicular to a board to measure the length of the shadow.

2. I needed two locations north and south of each other that fell along the same longitude, so that I could calculate a direct polar circumference.

3. I needed to find out when "noon" was, since daylight noon (the highest point of the sun) is not the same time as clock noon.

-------------------------------------------------------------
1. To fix some of the problems that stemmed from the last experiment I created a larger and better measuring stick.

Here is my handy assistant making calculations and measurements.
I used comments on my previous post to improve on this on. I increased the size of the vertical stick, chose a metal rod since it was not warped and not likely to become warped without noticing, and on the bottom I placed screw feet so I could adjust the levelness of the board.
High Noon time was set for 1:29 pm on both the day before and after the summer solstice.
From the previous post I am going to take 2 readings from two locations that are approximately along the same line of longitude. (C and B on the diagram below). From these I will calculate the difference in the angle and therefore can calculate the size of the Earth.

This time I went for a bit further and ended up at a distance of 66,758.87 m apart from each measurement. I had hoped this would help with the accuracy of the results.
I had double checked and my math previously was correct, where:
Circumference = Arc Length * Difference in the angles/360
For this experiment:Arc length = 66,758.87 mDifference in the angles = 1.4149 degress
C = 66,758.87 * 1.4149/ 360 C = 16,985.79 km
Still I am majorly off. Only by 57% this time. A 3% improvement. Good?
--------------------------------------------------------.
Next year I will perform the experiment again. This time with a larger measuring device and more distant measuring localities.

Stratigraphy.net | Impressum

Ads: