Charts, surveys and catalogs

We notice the importance of what and where.

Our astronomer, as recreational reading, is now deep into a book concerned with the names of stars.  We suppose the subject would be of interest to linguists, or more specifically philologists, those who trace words across time and place.  Or perhaps mostly to people concerned with mistakes in hearing and writing, for many of the names come from ancient Greek, but were transliterated or translated to Arabic, a quite unrelated language; thence again to Latin, again unrelated; and printed in early books and tables.  Often a name now belongs to no language ever spoken or written, being made up of tangled parts of several.

What has struck our astronomer this time, however, is the concern the author has with describing a star’s place in the figure of the constellation.  Quoting authorities ancient and less so, he will discuss whether it belongs on the shoulder, side or maybe arm.  And he is scathing about authors who describe these two stars as the eyes of the animal when they clearly mark the top of the head.

In this the book is similar to others in our possession written in the nineteenth century (this one is late, from 1899).  Several authors describing things to be found in the skies are careful about placing stars in the right place on a mythological beast or person.  In an age when any connection of stars with stories was long gone, why bother?

We think it has to do with a bit of technology and with the basics of map-making.  The placing of stars in a figure seems to die out early in the twentieth century, about the time that we first start to see popular-level star atlases.  When the art of printing had progressed to the point that a map of the sky could be put into anyone’s hands (rather than just the rich or well-connected), it was not longer necessary to describe locations.  One could show them.

We think this is an enormous advance.  As we’ve noted before, combining what and where in a two-dimensional display leads to a quite different way of perceiving and evaluating information.  With a glance at a map we see that the easiest route from here to there takes one side road, then the interstate the rest of the way.  But evaluating routes (to take just one task) is amazingly difficult for a computer, taking a lot of brainpower and even then not guaranteed to give the best answer.  It’s only in the last decade or two that acceptable algorithms have become widespread.  A computer, by its nature (so far), cannot glance at the map as a whole; it must go through the catalog of data piece by piece.

But now we have data sets that are impossible to map.  They are so enormous (millions of stars) and multidimensional (three-dimensional position, three-dimensional velocity, brightness, color, variability, etc.) that making a map is no longer a problem in printing technology, but in conception.  The display of information is an important current challenge.  Sometimes we feel we’re back in the days of “on the right shoulder of the Charioteer, the opposite side from the Chained Lady.”