Sky & Telescope - October 2022 - 74

BEGINNER'S SPACE by Diana Hannikainen
What Are
Constellations?
ORION
EVER SINCE THE DAWN of time, we've looked up into the
night sky and imagined stories in the patterns of the stars.
The concept of constellations, arbitrary groupings of stars
that represent familiar shapes, dates back more than 4,000
years to the ancient Sumerians. The Babylonians took the
pictorial concept one step further and listed stars in what
might be the first ever astronomical catalog, the MUL.APIN.
Surviving copies of this compendium date to the 7th century
BC, but they contain references to events several thousand
years earlier. Astronomy is an ancient science indeed.
Throughout the ages, civilizations around the globe have
imposed their own cultural histories and mythologies on
patterns in the sky. But it's Greek traditions that bring us the
constellations we're most familiar with today. And the person
responsible for this was the great Alexandrian astronomer
and geographer Claudius Ptolemaeus, commonly known
as Ptolemy. In his Almagest, written around AD 150, he listed
48 constellations, all but one of which are still extant today
(Argo Navis is split into three). Ptolemy drew upon mythologies
pertinent to him. And thus he lofted into the sky the
legend of Perseus, the Hero, who rescued Andromeda, the
Chained Maiden. (Perseus also lopped off the Medusa's head
to bring forth Pegasus, the Winged Horse.)
During the Golden Age of Islam, Arab astronomers such
as Muhammad Al-Battānī modified and expanded on Ptolemy's
scheme. We honor their legacy today in that we still
refer to many of the brighter stars by their Arabic names.
A Plethora of Patterns
For hundreds of years, the Ptolemaic system's status quo
held. Then the 15th century ushered in the Age of Exploration.
European navigators and adventurers sailed the globe
in search of trading routes, treasures, and spices. In so doing,
they opened up the Southern Hemisphere skies to astronomers
who headed to locations such as the Cape of Good
Hope and established observatories. Their exuberant explorations
of the southern skies yielded constellations honoring
exotic creatures, such as Tucana, the Toucan, and Piscis
Volans, the Flying Fish (today known simply as Volans).
After a period of relative soberness during which celestial
cartographers appeared to favor the sciences - as a result
THE HUNTER AND THE SEA-GOAT You may need to rely on your
imagination to discern the figures the constellations are meant to portray.
It's likely easier for you to picture Orion for the hunter he represents
than to see a goatlike creature in Capricornus, one of the constellations
of the zodiac. We still use the Arabic names for the brighter stars.
74 OCTOBER 2022 * SKY & TELESCOPE
α
Betelgeuse
γ
Bellatrix
Armpit
of the
Central
One
κ
β
Rigel
Left Leg
α
CAPRICORNUS
δ
γ
θ
β
ζ
ψ
ω
ALL IMAGES COURTESY OF AKIRA FUJI I
Sky & Telescope - October 2022

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