The glossary contains concise definitions of many of the important astronomical terms necessary to understand and make use of the data presented in The Astronomical Almanac. Its contents remain the same from year to year, but occasionally terms are added or dropped. The version presently available is consistent with the 2020 edition of The Astronomical Almanac.

The information is available as searchable HTML or as PDF. The PDF requires a reader such as Acrobat.

  • Glossary in HTML format
  • Glossary in PDF format
The Astronomical Almanac Online! 2020