Diurnal astronomy: using sticks and threads to find our latitude on Earth

TL;DR

This paper presents a simple, practical method using sticks and threads to determine Earth's latitude during daytime by analyzing shadow patterns, leveraging the relationship between shadows, time, season, and latitude.

Contribution

It introduces a novel, low-tech approach to accurately measure astronomical latitude using basic tools and shadow analysis during daytime.

Findings

Method allows high-precision latitude calculation during daytime.

Shadow patterns follow predictable paths related to Earth's geometry.

Technique is accessible and does not require complex equipment.

Abstract

It is well known that the length and orientation of a shadow cast by a vertical gnomon depends on the time of the day and on the season of the year. But it also depends on the latitude of the site of observation. During the equinoxes, the temporal sequence of the shadows cast by each of the points that form any object follows a straight line from west to east. A simple construction using sticks and threads can be used to materialize the plane of celestial equator's local projection, giving us a way to calculate our astronomical latitude during daytime with high precision.