Jordanus

Globe gores of the 1612 celestial globe by van den Keere & Plancius on which Plancius introduced his last set of biblically inspired constellations, including Jordanus (highlighted). Note that the year 1625 mentioned in one of the cartouches is not the year of publication but the epoch for which the stellar coordinates were plotted.

Jordanis Constellation Position on a modern map (CC BY Ultima Thulean)

Jordanus in Jakob Bartsch's Planisphaerium Stellatum 1661

An obsolete Early Modern constellation made from eight unnamed Ptolemaic stars: Alpha and Beta CVn, Alpha, 31 and 38 Lyncis (according to Toomer), and three fainter stars of uncertain identity.

Etymology and History

It is the name of a (real) river with immense cultural significance, not only as a border between countries but also for several religions. The English word is a Latin loanword, derived from Semitic 'Yard|on' 'flow down' <√ירד reflecting the river's declivity (Hebrew: נְהַר הַיַּרְדֵּן, Nəhar hayYardēn, Arabic: نَهْر الْأُرْدُنّ, Nahr al-ʾUrdunn).

Constellation

The extinct constellation "Jordanus Fluvius" or "Jordanis" – the river Jordan – was invented by Petrus Plancius on his 1612 celestial globe. The constellation first appeared in print in the book Usus Astronomicus Planisphaerii Stellati by Jacob Bartsch (1624), as his 26th constellation – "Iordanis" or "Iordanus". In the illustration of "Iordanis" on Bartsch's celestial globe Planisphaerium Stellatum... (1661), the star Alpha Lyncis appears as one of the prominent stars in the middle of the constellation. The extinct constellation also appeared as "Iordan" on Isaac Habrecht's (1628) Planiglobium coeleste et terrestre, "Fluvius Jordanis" in Carel Allard's (1708) Planisphaerii Coelestis Hemisphaerium Septentrionale and "Ior-Dan" in Corbinianus Thomas' (1730) Mercurii philosophici firmamentum firmianum. John Barentine (2016) notes that most of the area of Jordanis (and its aliases) was carved up in Hevelius's Lynx, Leo Minor, and Canes Venatici, which were subsequently adopted as constellations by the IAU in the 1920s.

Occurrence in historical maps and globes

• van den Keere, Pieter & Plancius, Petrus 1612, celestial globe.
• Bartsch, Jacob, 1624, Usus Astronomicus Planisphaerii Stellati, p. 57.
• Habrecht, Isaac, 1628, Planiglobium coeleste et terrestre, Figura I.
• Cellarius, Andreas, 1660, Harmonia Macrocosmica, Plates 24, 25 & 26.
• Royer, Augustin, 1679, Cartes du ciel reduites en quatre tables.
• Brunacci, Francesco, 1687, Planisfero del Globo Celeste Arctico & Antarctico.
• Coronelli, Vincenzo, 1693 & 1696, celestial globes.
• Allard, Carel, 1708, Planisphaerii Coelestis Hemisphaerium Septentrionale.
• Thomas, Corbinianus, 1730, Mercurii philosophici firmamentum firmianum, Frankfurt/Leipzig.

Transformation of Constellation

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  The eight 'external' stars south of Ursa Major in Dürer's star chart 1515, described by Ian Ridpath (highlighted by SMH).

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  Globe gores of the 1612 celestial globe by van den Keere & Plancius on which Plancius introduced his last set of biblically inspired constellations, including Jordanus (highlighted).

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  Jordanus constellation (highlighted) in Habrecht, Isaak, Planiglobium coeleste ac terrestre (1666).

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  Ursa Major on a celestial Globe by Isaac Habrecht (1675), (Dommuseum Hildesheim, Inv.-Nr. 1980-7). Jordanus is drawn with two headwaters labelled "Ior" and "Dan", and the Big Dipper is drawn as a Chariot with Charioteer pulled by three animals (instead of the handle of the dipper).

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  Image of the river with its direction of flow reversed by Johann ‍Ludwig ‍Andreae (1724) with description by Ian Ridpath

Mythology/ Cultural Significance

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  Bethabara at Jordan River (west), CC0.

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  Baptism ceremony at Bethabara, Jordan River (west), CC0.

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  Bethabara at Jordan River (west) where Jesus was baptised (according to Matthew) as ceremonial place, CC0.

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  Bethabara at Jordan River (west) where Jesus was baptised (according to Matthew) as ceremonial place, CC0.

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  Bethabara at Jordan River (west) where Jesus was baptised (according to Matthew) as ceremonial place and with a church visible at the east side of the river, CC0.

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  Probes of Jordan River water are sold as souvenirs, CC0.

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  The Jordan River defines the borders between Israel and Jordan. It has rich cultural and historical significance (CC BY SA 2.5 Author: David Bjorgen, from Wikimedia Commons).

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  Several churches at both sides of the Jordan River, cc0.

IAU Working Group Star Names

The name was suggested to the IAU WGSN to be used as a star name in 2023. Alpha and Beta CVn are already named (Cor Caroli and Chara), the brightest of the others is Alpha Lyncis (SIMBAD: 3.1 mag in V). For this star, also the star name "Xuanyuan" was suggested but rejected because of the tremendous significance of this Chinese term for the Chinese cultural heritage.

In the earliest versions of the drawing of the Jordanus River, the headwaters of the river are marked by three stars, likely to be identified with 25 CVn and 20 CVn + HR 4997. Their names in historical maps are Dan and Ior. Thus, it is proposed to name one, two or all three stars within the obsolete constellation:

1. α Lyncis: "Jordanus", (SIMBAD: 3.1 mag in V)
2. 25 CVn: "Ior" (SIMBAD 4.82 mag) for the sake of symmetry, perhaps also BH CVn (SIMBAD 4.94-5.1 mag VSX), but on some maps explicitly only one star here
3. 20 CVn + HR 4997: "Dan" (SIMBAD 4.69 mag, SIMBAD 4.94 mag)

The WGSN chose ... (not to apply/ to apply the name to a neighbouring star/ to ...) in the IAU-CSN.