Free the Globe

TL;DR

This paper explores the use of the parallel globe as an educational tool in astronomy, demonstrating its ability to teach about shadows, latitude, and local solar time through practical classroom activities.

Contribution

It reviews the parallel globe device and presents new classroom activities developed to enhance astronomy teaching using this simple instrument.

Findings

Parallel globe effectively demonstrates shadows and solar phenomena.

Activities improve teacher understanding and student engagement.

The method aids in visualizing Earth's rotation and regional differences.

Abstract

The parallel globe is an old, very simple and ingenious device that, when systematically employed in astronomy classes, becomes a teaching tool with great potential. Properly oriented according to the local meridian, this instrument allows us to follow the shadows in any region of the Earth that is illuminated by the Sun, as well as offering a clear view of the terminator, the fast-moving grey line that divides the day from the night on our planet. With knowledge of the shadows, it is possible to estimate the latitude of a site and to infer local solar time anywhere in the planet's sunlit hemisphere. Furthermore, by using the parallel globe we may understand simply the existence of regions in which objects sometimes do not cast shadows, and also other regions which, on the contrary, sometimes become "long-shadow" countries. In this work, we first review the device and the basics of its assembly and operation. In the second part, we describe in detail some activities targeted to facilitate its use in the classroom, which our research group has been developing during teacher training workshops.