Brazil, Uruguay and Argentina joint observation of March 2009 equinox

NESTOR CAMINO; ALEJANDRO GANGUI; ET AL.

Rio de Janeiro, Brasil

Congreso; XXVII General Assembly of the International Astronomical Union; 2009

International Astronomical Union (IAU)

This year, March equinox took place on the 20th, at 11:44 (GMT). For this occasion, a didactic activity on topics of Astronomy, coordinatedand carried out at the same time in nine cities of Argentina, Brazil and Uruguay, has been organized. The idea for this project wasdeveloped by the Task Group on Astronomy Teaching at the CTS4 Meeting (Ciência, Tecnologia e Sociedade IV), which took place in Porto Alegre in November 2008.Professors and researchers in Astronomy Teaching took part together with their students, mainly pre-service elementary and secondary level teacher students, measuring the shadows cast by several vertical gnomons and materializing sun rays passing through the top of the gnomon by means of threads. Parallel Earth globes were utilized in each location too, so as everyone could visualize in real time its local position as well as a planetary perspective which included the rest of the partners, materialized by small sticks as gnomons in each place.The activity allowed us to explore concepts such as local horizon, local meridian, cardinal points, astronomical latitude, equinoxes and solstices, plane of Celestial Equator’s local projection, differences between solar and mean time, etc. The educational key of this activity is the observational 3D treatment of those concepts, very different from a more classical and sole theoretical approach.The experiments performed by many groups in different cities emphasized aspects that are characteristic to each place (times of solar noon, length of the shadows, inclination of equatorial planes, etc.) and others that are common to all, such as the straight line followed by the tip of the shadow on that date, which materializes the East-West line, length of day and night, points of sunrise and sunset on the local horizon, etc.We here report the main aims of the activity, details of the measurements and some of the results obtained by the different groups in the three countries, as well as a comparison amongst not only the astronomical aspects of this experience but of the social and educational ones as well. [31 authors from 3 different countries in total.]