Unpacking the Hertzsprung-Russell Diagram - A Social Semiotic Analysis of the Disciplinary and Pedagogical Affordances of a Central Resource in Astronomy

Oct 15, 2026

The paper applies a social semiotic analysis to the Hertzsprung-Russell (H-R) diagram, treating it as a central astronomy resource whose representation mediates both disciplinary and pedagogical meaning. It argues that layered astronomical knowledge and historical anomalies create counterintuitive features that reduce the diagram’s pedagogical affordance and may form barriers to student disciplinary learning. Using the analysis as a case study, the work generalizes four barrier types and recommends unpacked resources to help lecturers explicitly surface disciplinary affordances for learners.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages9

Reading Time23 min

AccessFree to download

Introduction

Disciplinary knowledge and representation

Social semiotic approach

Disciplinary and pedagogical affordance

Relationship between the two affordances

Airey, J., and Eriksson, U. (2019). Unpacking the Hertzsprung-Russell Diagram: A Social Semiotic Analysis of the Disciplinary and Pedagogical Affordances of a Central Resource in Astronomy. Designs for Learning, 11(1),99–107. DOI: [https://doi.org/10.16993/dfl.137](https://doi.org/10.16993/dfl.137) | RESEARCH
Unpacking the Hertzsprung-Russell Diagram: A Social Semiotic Analysis of the Disciplinary and Pedagogical Affordances of a Central Resource in Astronomy
John Airey*,† and Urban Eriksson‡,§ | | --- | | In this paper we are interested in the relationship between disciplinary knowledge and its representation. We carry out a social semiotic analysis of a central tool used in astronomy—the Hertzsprung-Russell (H-R) diagram—in order to highlight its disciplinary and pedagogical affordances. The H-R diagram that we know today combines many layers of astronomical knowledge, whilst still retaining some rather quirky traces of its historical roots. Our analysis shows how these ‘layers of knowledge’ and ‘historical anomalies’ have resulted in a number of counterintuitive aspects within the diagram that have successively lowered its pedagogical affordance. We claim that these counterintuitive aspects give rise to potential barriers to student disciplinary learning. Using our analysis as a case study, we generalise our findings, suggesting four types of barrier to understanding that are potentially at work when students meet disciplinaryspecific semiotic resources for the first time. We finish the paper by making some general suggestions about the wider use of our analysis method and ways of dealing with any barriers to learning identified. In the specific case of the H-R diagram, we suggest that lecturers should explicitly tease out its disciplinary affordances by the use of ‘unpacked’ resources that have a higher pedagogical affordance. | | Keywords: Disciplinary affordance; Pedagogical affordance; Graphs; Disciplinary learning; Astronomy education; Social semiotics | Introduction The Hertzsprung-Russell (H-R) diagram is one of the most utilized tools in astronomy and astrophysics. Essentially it is a plot of the brightness of a star against its surface temperature, with the resulting position of the star in the diagram allowing astronomers to infer a wealth of information about the star’s make-up, evolution, age and ultimate fate. Atypical example ofthe H-R diagram can be found in Figure 1. As disciplinary insiders, when astronomers look at the H-R diagram in Figure 1 they automatically discern a wealth of disciplinary knowledge. But what do students discern when they first encounter it? What meaning can this resource convey and how is that meaning constructed by students? Naturally, the most obvious way to address this question is to ask the students themselves about * Department of Physics and Astronomy, Uppsala University, Uppsala, SE † Department of Mathematics and Science Education, Stockholm University, Stockholm, SE ‡ National Resource Centre for Physics Education, Department of Physics, Lund University, Lund, SE § Department of Science Education, Faculty of Education, Kristianstad, University, Kristianstad, SE Corresponding author: John Airey ([john.airey@mnd.su.se](john.airey@mnd.su.se)) their disciplinary discernment (Eriksson, Linder, Airey, & Redfors, 2014) and this is indeed the path this project will be taking in the future (Eriksson et al., in preparation) . However, in order to guide our questioning of students, we decided to first examine the H-R diagram itself in order to audit the ways in which it represents disciplinary knowledge. In this paper we adopt a social semiotic approach which has been defined as “the study of the development and reproduction of specialised systems of meaning making in particular sections of society”(Airey & Linder, 2017, p. 95) . Our claim is that this kind of analysis can be used to help teachers identify potential barriers to student learning. Put simply, we

FAQs

What is the focus of the paper regarding the Hertzsprung-Russell diagram?

It examines how the H-R diagram represents disciplinary knowledge and how that representation supports or hinders student learning through disciplinary and pedagogical affordances.

What method does the authors use to analyze the diagram?

The paper uses a social semiotic approach to analyze the development and reproduction of specialized systems of meaning within astronomy education.

How do the authors explain the reduced pedagogical affordance of the H-R diagram?

They argue that historical anomalies and layered knowledge produce counterintuitive aspects that act as potential barriers to student disciplinary learning.

Oct 15, 2026

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