The parallel globe: a powerful instrument to perform investigations of Earth’s illumination

Abstract

Many researches document difficulties by learners of different ages and preparation in understanding basic astronomical concepts. Traditional instructional strategies and communication media seem not effective in producing meaningful understanding or even induce some misconceptions and misinterpretations. In line with recent proposals of pedagogical sequences and learning progressions about core concepts and basic procedures in physics and astronomy education, in this paper we suggest an intermediate, essential, step in the teaching path from the local geocentric view of the Earth-Sun system to the heliocentric one. At this aim we present data collected along a day and a year through an instrument we call "Parallel Globe", a globe positioned locally homothetic to the Earth we live on. Some analyses are suggested, in particular about the phenomenon of illumination of the Earth and its variations, consistent with the proposed instructional objectives.

Exploring the reasons for the seasons using Google Earth, 3D models, and plots

“…Critical features of our Google Earth-based models include: (i) a representation of the ecliptic plane at a fixed angle of 23.5°to the Earth's axis; (ii) the display of a fixed right ascension/declination (r.a./dec) grid under which the Earth spins; (iii) a clear separation of Earth's daily spin on its axis from the annual migration of the midday Sun's central ray along the ecliptic; (iv) tools that enable students to measure variations in the azimuth of sunrise and sunset, the altitude of the midday Sun, and the length of the day; (v) rotational interactivity that removes the ellipse-generating effect of oblique viewing; (vi) access to Google Earth's 3D terrain, historical imagery, and weather layer, which can help students appreciate geographic contributions to seasonal effects, bearing witness to the lag between solstices and climate maxima; (vii) the Google Earth search box that allows students to zoom in on their home location -a virtual 'parallel globe' (Rossi, Giordano, and Lanciano 2015); and (viii) a teaching sequence from geocentric Google Earth models to heliocentric plots and digital astronomy applications such as Stellarium, Celestia, and Starry Night Pro.…”

TheSky on Earthproject: a synergy between formal and informal astronomy education

“…In those occasions, we had the opportunity both to further involve children, teachers and parents in out-of-school science education and to investigate deeply the Parallel Globe's potentialities. At the end of that experience, we were able to define how to use the Parallel Globe to investigate the phenomenon in a systematic way, analyse the collected data and interpret them [19]. As one of the educators was directly involved in collecting data, the experience also became a further professionalising occasion.…”

“…The first tool can be used to measure the solar altitude-azimuth coordinates for each position recorded on the grid surface and can be considered an evolution of the bamboo canes. The other one can be used to visualise daily and annual changes of the Earth's illumination and deduce how local illumination conditions change depends on the observer position (for a detailed discussion see [19]). Using them together, students have the chance to deeply explore the local and geocentric seasons' perspectives, constructing the necessary phenomenological knowledge to meaningfully move toward the heliocentric model.…”

Teaching Physics through Astronomy: an object-based approach

“…This feedback encouraged us to use elements of the OBL approach in the development of ATENA, the year-long teacher training program that followed-up the two workshops. During this program we delved deeper into the study of light and its connections with astronomy through the exploration of more instruments, such as quadrants, solar clocks, the "parallel globe" [27], and a home-made apparatus for measuring the speed of light. Further insights are expected from the school experimentation conducted as part of the ATENA program.…”