A Remarkable Scatterplot

The Hertzsprung-Russell diagram, invented by astronomers just after the turn of the century, has had a profound influence on almost every aspect of modern astronomy, but especially on theories of stellar evolution.The diagram is an excellent pedagogical example of a scatterplot and is remarkable on many counts: it is an impressive illustration of the power of graphical display; it may be used to show the strengths and limitations of smoothing, or the fitting of parametric functions; and variations of the plot can be used to represent change over time, large numbers of data points, or differing relationships in distinct strata.