From the April 2007 issue

Can you explain why irregular constellation boundaries appear in various star atlases?

Jack Whitman, Philadelphia
By | Published: April 1, 2007 | Last updated on May 18, 2023
The 88 constellation boundaries were formalized in 1928 by a commission sanctioned by the International Astronomical Union. A publication announcing the boundaries appeared in 1930, authored by Belgian astronomer Eugene Delporte. This publication gave strict boundaries for each constellation. It left no blank spaces between constellations, and there was no overlap or shared stars. No variations exist between star atlases currently in use.

But in star atlases of a century ago, astronomers chose to follow historical precedent and kept many borders as they had been known for centuries. This explains much of the “wandering nature” of the constellation boundaries. But most, if not all, star maps published since 1930 show the same boundaries. — Michael E. Bakich, Senior Editor