Why space objects have alphanumeric names instead of poetic ones

Space · Published 25 October 2026 Swipe more like this →

In short: When you see a name like RX J1131−1231, you aren't looking at a typo. It is a precise coordinate in a massive cosmic filing system. Because the universe contains billions of objects, astronomers prioritize unique identification over evocative storytelling to ensure every discovery has a specific home.

The naming of the cosmos is governed by the International Astronomical Union (IAU), an international association of professional astronomers founded in 1919. The IAU is tasked with safeguarding the science of astronomy, which includes the official assignment of designations and names to celestial bodies and their surface features. To understand these names, one must first distinguish between a "name" and a "designation." While a name is a term used in everyday life, a designation is a strictly alphanumeric code used almost exclusively in official catalogs and professional research.

For new stars, the standard practice is to use alphanumeric designations because star catalogs now contain billions of objects. A sequence value and a primary acronym usually form these codes. While the acronym denotes a particular source collection, the sequence value serves as a unique character string for a specific item inside that group. This system ensures that even in a crowded sky, two different objects never share the same identity.

Different types of celestial bodies follow different naming conventions. Supermassive black holes are often numbered based on the galaxy they inhabit, such as those derived from the New General Catalogue (NGC) or the Messier objects (M). In contrast, stellar black holes are often cataloged by their constellation and discovery order. Numerous black holes use their celestial coordinates for naming, with the initial survey or tool used for discovery, like the Chandra X-ray Observatory, added as a prefix.

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