The Periodic Table of Messier Objects

Mike Keith, 2014

In May 2013 I finished photographing all 110 Messier objects, a project that took about 11 months, and by 2014 had rephotographed every object with somewhat better quality.  I wanted to make a poster out of the 110 photos, and after a little thought I realized that there is another famous collection of objects (which also number a little over 100) that are usually displayed in an arrangment of tiles divided into categories.  So with that in mind I attempted to create an arrangement of the Messier Objects inspired by the Periodic Table.  The result is shown below.

If you are interested in a print of this poster or access to a high-resolution digital version, contact me.  Otherwise, please do not copy or distribute it without permission.

In this chart,

- Each box contains a photo of a Messier object with labels indicating its Messier number, constellation, R. A. in hours, magnitude, and size in arcminutes (see legend on the right side of the chart).  If the object is approximately circular then there is only one size number, otherwise the size of the major and minor axes (e.g., "9x6") are shown.  If the object is a galaxy then the galaxy type is also shown in the bottom right just above the size number(s).  Each photo is oriented with North up and East to the left.

- Objects are grouped into rows by five major categories: stars, nebulae, galaxies, and clusters.  Each of these categories is divided into two subcategories, as shown in the color key on the right side of the table.  As a result of putting the stars category in the top row and the supernova remnant subcategory on the left, Messier 1 occupies the same place in our chart as does element 1 (hydrogen) in the chemical periodic table.

- Within each of the 8 subcategories (i.e., within each set of objects whose tile text is the same color), the Messier objects are not ordered by their M number but rather by what seemed to be a better scheme: they are arranged in the chart roughly according to their position in the sky, with the top and bottom rows of a section containing the more northerly and southerly objects (respectively) and objects in each row or subrow positioned according to their R.A. in the sky, from 0h on the right to 24h on the left.  This allows one to see from the chart which Messier objects are visible on a given date and time.  The R.A. hour number shown under the constellation name further assists in this.

It is important to note that astronomers are not 100% certain of the identity of M102.  One school of thought holds that it was a duplicate observation of M101; the other is that it is NGC 5866.  In order to not have to omit M102 from the chart we have chosen the latter option (NGC 5866).