Look up on any clear night and the stars you can point at almost all have names older than the telescope. But star names are not folklore left to drift: since 2016 the International Astronomical Union has run an official list, and a star's proper name is now a matter of record. Here is how that works, the named stars worth knowing, and the clouds of glowing gas that hang behind them.
Who names the stars?
The IAU's history of star naming (read 4 September 2026) records that until recently, famous stars like Betelgeuse and Rigel "had no official spelling" - stars sometimes carried several names, and sometimes different stars shared one. The IAU's Working Group on Star Names was set up to fix that, and has approved proper names for roughly 449 stars so far.
Two systems coexist. The proper name is the old one: Sirius, Vega, Aldebaran. The designation is the catalogue code professional astronomers use - Betelgeuse is also Alpha Orionis, HD 39801, HR 2061 and several other identifiers at once, which is why the IAU's intervention on spellings mattered.
And the lineage of the names? The IAU puts it plainly: most modern star names are the product of "translation, misunderstandings, abbreviations and transformation from the original Greek texts to Arabic to mediaeval Latin and modern languages". Some names never changed at all - Sirius appears in Hesiod's Works and Days in the 8th century BCE.
Orion, the constellation everyone can find
The constellations themselves are also official. At its first General Assembly in Rome in 1922 the IAU agreed a list of 88 constellations covering the entire sky, with defined boundaries - so every object in the sky belongs to exactly one of them.
Orion is the one almost everyone learns first, and its brightest stars are all on the IAU's approved list, each with its Bayer designation from the old scheme of labelling stars by Greek letter:
- Betelgeuse - Alpha Orionis, the red giant at the hunter's shoulder, described by the IAU as "the red giant in the constellation Orion".
- Rigel - Beta Orionis, the blue-white balance point on the opposite corner.
- Bellatrix - Gamma Orionis.
- Alnitak, Alnilam and Mintaka - Zeta, Epsilon and Delta Orionis, the three stars of the belt, close enough in a line that you can check them against this page tonight.
- Saiph - Kappa Orionis, and Meissa - Lambda Orionis, at the head.
Find the belt and the rest of the figure follows - which makes Orion the reliable winter signpost from which the other constellations are usually taught.
The named stars beyond Orion
The IAU list runs far beyond one constellation, and a few names are worth knowing on sight:
- Sirius - the name is unchanged since Greek antiquity; Hesiod wrote it down in the 8th century BCE, though it was absent from Ptolemy's later Almagest catalogue.
- Polaris - the pole star, approved by the IAU in 2017, standing almost still while the whole sky turns.
- Vega - the IAU's own example of the difference between a proper name and a designation (also HD 172167).
- Aldebaran, Antares, Arcturus, Canopus, Capella, Procyon, Regulus, Spica - the rest of the ancient set the IAU lists as unchanged since Greek antiquity, one bright marker per region of sky.
The pattern behind almost all of them: a Greek description, translated into Arabic as astronomy travelled through the mediaeval world, then Latinised and kept. The names are fossils of the history of the science.
The glowing clouds: what a nebula actually is
Behind and between the stars sit the nebulae - NASA describes them as "enormous clouds of dust and gas occupying the space between the stars". Not all are alike, and the differences are the interesting part.
An emission nebula glows on its own: stars heat the surrounding gas and its atoms respond by lighting up - NASA's comparison is a neon sign in a shop window. A reflection nebula does the opposite: NASA describes it as "like fog around a street lamp" - it shines only because dust scatters the light of a star embedded in it, and emits no visible light of its own. Reflection nebulae take on a bluish cast because their dust grains preferentially reflect blue starlight.
Orion happens to hold examples of both. The famous Orion Nebula is the emission kind; nearby sits NGC 1999, a reflection nebula imaged by Hubble weeks after the 1999 repair mission, illuminated by a bright, recently formed star. The whole region is a stellar nursery - which is why the same patch of sky serves both as constellation and as laboratory.
For the planets that wander in front of these fixed patterns, read the planets in order - the pair together cover most of what is overhead. Both live in Looking up, the free-reading half of the site, and the patterns these stars sit in are drawn out in our constellation prints.
