Custos Messium

A constellation named after Charles Messier

In 1775, French astronomer Jerome de Lalande proposed to name a constellation after and in honor of his colleague Charles Messier: "Custos Messium", the Guardian of the Crops, or the Harvest Keeper. He proposed this because "the name will recall to the memory and recognition of astronomers yet to come, the courage and zeal of our most indefatigable observer, Messier, who, since 1757, seems to be in charge of guarding the sky and discovering the comets."

This constellation, though only short-lived and longly extinct now, found its way on a new celestial globe by Lalande, the French edition of Flamsteed's atlas, and Bode's Uranographia.

Custos Messium was situated not far from the North Celestial Pole, between and formed of bordering stars of Cassiopeia, Cepheus and Camelopardalis; one of its principal stars was double star 40 Cassiopeiae. It is circumpolar even for mid- and even rather low Northern latitudes. According to Messier's notes, Lalande selected this area of the sky because the comet of 1774 (1774 Montaigne) has appeared in this region of the sky. It happens that Custos doesn't contain any Messier object, not even a remarkable NGC or IC object, and consists of considerably faint stars only.

Richard Hinckley Allen (1899) speculates that the name also may have been "induced by the fact that the two neighboring royal personages [Cas and Cep] were rulers of an agricultural people, and the Giraffe [Cam] an animal destructive to grain-fields; all perhaps selected because the Phoenicians are said to have imagined a large Wheat Field in this part of the sky."

During his activity as astronomer, Lalande has also proposed two other constellations:

All these creations were never widely accepted, but appeared e.g. in Johann Elert Bode's star atlasses. In turn, Lalande also included in his charts the Prussian constellations Sceptrum Brandenburgicum (the Brandenburg Scepter, invented by Kirch in 1688) and Frederici Honores (Friedrichs Ehre, Bode's 1787 creation). Meanwhile, they all have longly disappeared from the sky maps.

Some corrections in this page were contributed by Dr. Nick Beeson, thanks!


Hartmut Frommert
Christine Kronberg

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Last Modification: August 23, 2006