Constellation Reference
IAU constellations with abbreviation and genitive case.
Overview
The Constellation Reference is a searchable table of the 88 modern constellations as recognised by the International Astronomical Union. Each row carries the English name, the official three-letter IAU abbreviation, the Latin genitive case (used in star names like "Alpha Centauri") and a brief note on the hemisphere or family the constellation belongs to.
The tool is built for amateur astronomers labelling sky charts, astrology and mythology writers double-checking their Latin and students preparing for an astronomy exam. It answers long-tail queries like "IAU constellation abbreviation Cygnus", "Latin genitive of Orion", "how many official constellations are there" and "Bayer designation genitive case lookup".
How it works
The dataset is the canonical IAU list, fixed since 1930 when the boundaries were formally drawn. The three-letter abbreviation is the official short form used in Bayer and Flamsteed star designations — for example, the brightest star in Cygnus is α Cygni, where "Cygni" is the genitive form.
Searching is a case-insensitive contains match across name, abbreviation and genitive, so you can type either "ori", "Orion" or "Orionis" and land on the same row. The table also tags each constellation as primarily northern, southern, equatorial or zodiacal.
Examples
Orion → Ori, Orionis, equatorial
Cygnus → Cyg, Cygni, northern (Milky Way)
Sagittarius → Sgr, Sagittarii, zodiacal, southern
Crux → Cru, Crucis, southern (Southern Cross)
FAQ
Why are there 88 constellations and not more?
The IAU fixed the modern list at 88 in 1930 with formal sky boundaries so every point on the celestial sphere belongs to exactly one constellation. Many older traditions had more — or differently named — patterns.
What is the Latin genitive for?
The genitive is used in star names like "Sirius is α Canis Majoris" — Canis Majoris being the genitive of Canis Major. It indicates "of" or "belonging to" the constellation.
Are constellation names always Latin?
The official names are Latin or Latinised. Common English names like "Big Dipper" or "Plough" refer to asterisms — patterns within a constellation — not formal constellations.
Which is the largest constellation?
Hydra covers the largest area of sky, followed by Virgo and Ursa Major. The smallest is Crux (the Southern Cross), despite its iconic status.
Do the zodiac constellations match the astrological signs?
The 12 astrological signs evolved from 12 ancient constellations, but precession of Earth's axis has shifted the alignment significantly. There is also a 13th zodiacal constellation, Ophiuchus, that the Sun passes through.