Albireo is a double star designated Beta Cygni (β Cygni), or (per the International Astronomical Union) specifically the brightest star in the system. Name’s gotta be Arabic, like Alcor and Aldebaran, right? Wrong! Per that Wikipedia article:

The system’s traditional name Albireo is a result of misunderstanding and mistranslation. It is thought that it originated in the Greek name ornis for the constellation of Cygnus, which became urnis in Arabic. When translated into Latin, this name was thought to refer to the Greek name Erysimon for the plant called Hedge Mustard (Sisymbrium officinale, which in Latin is ireo), and so was described in Latin in the Arabo-Latin Almagest of 1515 as “Eurisim: et est volans; et jam vocatur gallina. et dicitur eurisim quasi redolens ut lilium ab ireo” (“Eurisim: and it is the flyer, and now it is called the hen, and it is called Eurisim, as if redolent like the lily from the ‘ireo'”), via a confusion between ireo and the scented flower Iris florentina. This was variously miscopied, until “ab ireo” was treated as a miscopy of an Arabic term and changed into al-bireo.

Isn’t that great? (It reminds me of the spurious dogs of Canes Venatici.) Thanks, Adrian!


  1. Beta Cygni denotes (as you would expect) the _second_ brightest star of the constellation Cygnus, with magnitude 3.3. The brightest star is Deneb, aka Alpha Cygni, magnitude 1.25.

  2. Right, but the reference is to the brightest star of the (double-star) system, not the constellation.

  3. The name of the star Deneb is, for me, forever associated with this sentence from “The Feeling of Power”: “He smoked Denebian tobacco with the air of one whose patriotism was so notorious, he could be allowed such liberties.”

  4. It is obvious to me that this name has to be restored to the original and correct form. And ‘decimate’ does refer to every tenth man.

  5. I don’t understand the urnis > erysimon step (among other things).

  6. David Eddyshaw says

    The name Albireo inevitably brings to mind the explanation in The Hitchhiker’s Guide to the Galaxy as to why you can never find a biro:

    And it was to this planet that unattended biros would make their way, slipping away quietly through wormholes in space to a world where they knew they could enjoy a uniquely biroid lifestyle, responding to highly biro-orientated stimuli, and generally leading the biro equivalent of the good life.

  7. Technically β Cyg is two stars, A and B, but we don’t know if they are a double star (if so, the period must be > 10⁵ years) or just a visual coincidence.

    Albireo sounds to me like the common name of a bird, probably a brightly colored one. Go figure.

  8. David Marjanović says

    brightly colored

    Pretty much.

  9. Trond Engen says

    Let that go vireal.

  10. Yes, but the alb- part looks like ‘white’.

  11. January First-of-May says

    as to why you can never find a biro

    …Huh, that makes far too much sense. I know I’ve been regularly buying the darn Tz-1156s by the half-dozen at some point, and yet I hardly ever see any at home.

    (I would still have been buying them by the half-dozen, but the shop I got them from stopped offering them many years ago.)

  12. Cf. “Or All The Seas With Oysters”, Avram Davidson’s explication of the Miracle of Metamorphosis as applied to common household objects — or are they?


  1. […] Hat notes how translation mistakes led to the star Beta Cygni gaining the Arabic name […]

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