Author: Alexandre Costa
Country: Portugal
Co-Author(s): Ricardo Moreno
Affiliation: Colegio Retamar
Country: Spain
Rosa Ros
Affiliation: Universidad de Catalunia
Country Spain
Beatriz García
Affiliation: Instituto de Tecnologías en Detección y Astroparticulas
Country: Argentina
Wanda Diaz-Merced
Affiliation: OAD
Country: South Africa/Puerto Rico
Lina Canas
Affiliation: OAO
Country: Japan
Kathy Eastwood
Affiliation: Northern Arizona University
Country: USA
Title: “Photometers and Photometry in Astronomy: The global inclusive campaign to Determine the Sun’s power”
Bunsen invented the oil spot photometer. His photometer used a piece of paper located in between two light bulbs that were separated by a measuring tape. To do so, just place both light sources on the ends of a tape measure. A plain white paper with a small oil stain is placed between the sources. In the stained area, the paper becomes semi-transparent1. When moving the paper between the two sources of light, there comes a time when the stain is barely visible. In this position, the illuminance that reaches both sides of the paper is the same. Illuminance is the flow that arrives per unit area.
In this proposal, instead of using a paper stained with oil like Bunsen we propose to use our cheeks and/or hand or ears. On a sunny summer day, it is possible to compare the heat that comes from the Sun on one of the cheeks of the face and the heat that comes from a 100 W bulb in the other. The distance of the bulb to the face/hand should be changed until the student has exactly the same feeling of heat in the skin of both cheeks/side of hand. Measuring the distance d of the bulb to the face/side of hand and the known distance R to our Sun (150 x 10**9m), we can estimate the luminosity of the Sun using the formula of the law of the inverse of the squares. This proposal shows adaptations to carry the lesson indoors and using audio.
This presentation shows the results of the global campaign to determine the Sun’s power proposed as part of the 100 years under one sky celebration.
References:
[1]: The Power of the Sun and How to Measure it http://sion.frm.utn.edu.ar/NOC-Argentina/wp-content/uploads/2018/12/Sun-Power-how-to-mesure-IAU100-ENG.pdf