Sky & Telescope - May 2023 - 31

TYCHONIS BRAHE ASTRONOMIÆ INSTAURATÆ MECHANICA / WIKIMEDIA
COMMONS / PUBLIC DOMAIN
name al-nath (Butting Animal) onto the Beta star of Taurus,
the Bull, even though it originally denoted two stars in Aries,
the Ram. The spelling has since been changed to Elnath.
Applied Imagination
Two of the names in the Palermo Catalogue are pure fabrication:
Sualocin and Rotanev, for Alpha and Beta Delphini,
respectively. Read backwards, these become Nicolaus Venator,
a Latinized form of Niccolò Cacciatore. Apollo astronaut
Virgil Ivan (Gus) Grissom pulled a similar stunt by smuggling
his own middle name spelled backward as Navi to denote
Gamma Cassiopeiae on the star charts used to navigate to the
Moon. The IAU approved Sualocin and Rotanev because they
have been widely used for two centuries, but it has not yet
made a decision on Navi.
Plenty of other star names have been coined without any
hidden agenda, first in Latin and most recently in English.
Two obvious Latin examples are Polaris, which marks the
north celestial pole, and Mira (Latin for amazing), which varies
in brightness 100-fold every year.
Surely the most unimaginative English star name is Peacock,
applied to the Alpha star of Pavo, the Peacock. However,
the name does the job beautifully - it's a short, easily
recognized label on charts for celestial navigators in the
Southern Hemisphere. The star has no traditional Western
name because it's too far south to be visible from Greece,
Mesopotamia, or Egypt.
When European navigators ventured south of the equator
in the 1500s, they needed names for all the uncataloged stars
they encountered. One ploy was simply to move an existing
name to one of the new stars. The name Achernar, from
akhir al-nar (River's End), originally denoted the star Theta
Eridani, which was the southernmost end of Eridanus, the
River, in ancient times. In the late 1500s celestial cartographers
extended Eridanus south to dazzling Alpha Eridani, and
the name Achernar was quite logically then transferred to
Alpha, the new River's End. That left Theta anonymous until
it acquired the name Acamar, a different abbreviation of the
same Arabic phrase.
There are many other cases in which a single name has
been used for two different stars. Conversely, most star names
have spelling variants, and quite a number of stars have two or
more unrelated names. To take one prominent example, 20thcentury
star atlases and catalogs are split roughly 50-50 with
respect to the Beta star of Cetus, the Sea Monster. Some call
it Deneb Kaitos, from dhanab qaitus, the Sea Monster's Tail,
while others call it Diphda, from its folk-Arabic name al-difdi
al-thani, the Second Frog. The IAU endorsed Diphda in 2016,
so with any luck that name will be used in all future atlases.
21st-Century Star Names
Lack of standardization is rarely a problem in casual conversation
or writing since all languages are chock-full of words
with many meanings and meanings with many words. But
when telescopes with Go To capability became practical,
THE DAWN OF MODERN OBSERVING Like Ulugh Beg 150 years
earlier, Tycho Brahe (1546-1601) was a wealthy nobleman who built an
observatory to measure planet and star positions. But whereas Ulugh
Beg was an enlightened outlier in an increasingly fundamentalist society,
Brahe worked at a time when scientific inquiry was in full flower. His data
set a new standard for observational excellence and prompted Kepler's
insight that planetary orbits are elliptical.
sk yand tele scope .o r g * MAY 2023 31
manufacturers rashly chose to identify stars by name rather
than designation. That can be a problem if you're looking for
Deneb Kaitos in your star atlas, but the scope calls it Diphda
instead. The situation could have been avoided if star names
had been standardized much sooner.
As worthy a goal as standardization is, that's not why the
IAU got into the star-name game. " It all started with the
desire to name exoplanets, " explains Eric Mamajek, chair
of the IAU Working Group for Star Names (WGSN). There
are well-established procedures for naming newly discovered
solar system objects, but not for planets orbiting other stars.
This becomes a problem whenever a newsworthy exoplanet is
discovered, because news media and the general public much
prefer names to convoluted designations. So far, they've made
do with phrases like " the diamond planet " for the carbonrich
planet around 55 Cancri, or " the Tatooine planet " for
Kepler-16b, which, like the eponymous Star Wars planet,
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Sky & Telescope - May 2023

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