# Constellation names, abbreviations and genitives

Learn which name to search, what a Latin genitive means, and how to read labels such as Alpha Orionis or UMa.

## Which name identifies the constellation?

The Latin name identifies the same constellation in every language version. Orion, for example, remains Orion when the common name changes with the selected language. A translated common name helps you recognise the entry; it is not a second constellation.

The astronomical catalogue describes sky regions. Familiar names can also occur in mythology or astrology, but those uses do not change the boundaries or the meaning of a catalogue entry.

## What do the three-letter abbreviations mean?

Each constellation has a standard three-letter abbreviation: And for Andromeda, Ori for Orion and UMa for Ursa Major. Capitalisation belongs to the standard form; UMa combines the two words in its Latin name.

You can search this site with a Latin name, a supported common name or a three-letter abbreviation. Search accepts different letter case. To compare an entry with a chart or another catalogue, copy the standard abbreviation shown in the detail page.

## What is the Latin genitive?

The genitive is the possessive form of the Latin constellation name, used in star designations. Orion becomes Orionis, so Alpha Orionis means the star designated Alpha in Orion. Andromeda becomes Andromedae; Ursa Major becomes Ursae Majoris.

A genitive is not a translation, an alternative sky region or a brightness measurement. Latin endings vary, especially in names made of more than one word, so use the complete genitive field rather than adding an ending yourself.

## Does Alpha always mean the brightest star?

No. Bayer designations combine a Greek letter with the constellation’s genitive, but the letters are not a reliable brightness ranking. In Gemini, Pollux is Beta Geminorum and is brighter than Castor, Alpha Geminorum.

A star can also have a proper name and several catalogue designations. Betelgeuse and Alpha Orionis refer to the same star. Use the chart’s magnitude key to interpret brightness instead of judging it from a Greek letter.

## How can I learn the fields without mixing them up?

Start with the Latin name and abbreviation as a pair, such as Orion ↔ Ori. Reveal a learning card to check the common name and genitive. Practise the reverse direction when the abbreviation is familiar.

Use the detail page when you need the exact genitive or chart. Pronunciation hints on this site follow English reading conventions; they are not audio recordings or pronunciation guides for every selected language.