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The sky is divided up into 88 areas, known as constellations, which serve as a
convenient way of locating the position of stars in the sky. Constellations come in
many different shapes and sizes. Some constellations consist of easily recognizable
patterns of bright stars, such as Orion, while others are faint and difficult to identify.
The tradition of dividing the sky into constellations began thousands of years
ago when ancient peoples assigned certain star patterns the names of their gods,
heroes, and fabled animals. With few exceptions, the star patterns bear very
little resemblance to the people and creatures they are supposed to represent; the
connections are symbolic rather than literal.
The ancient Greeks recognized a total of 48 constellations. Various other
constellations were added at later times. Early cartographers were free to introduce
new constellations of their own invention. In 1930, the International Astronomical
Union, astronomy's governing body, adopted the list of 88 constellations, and set
their exact boundaries.
2.3.2
Constellations
Constellation maps represent some of the most imaginative organizational
metaphors that hold isolated starts in an intact image. Here we highlight the
metaphorical details concerning the constellation figures such as Andromeda and
Orion the Hunter so as to identify the nature of metaphoric representations.
The French astronomer Charles Messier (1730-1817) created a catalog of
nebulae and star clusters. The Messier catalog lists 110 deep sky objects cataloged
by M numbers: M1 through M110. Pictures of Messier objects are accessible from
the web, for example, the Messier picture gallery.
1
John Louis Emil Dreyer (1852-
1926) published the New General Catalogue (NGC) in 1888 as an attempt to make
a complete list of all nebulae and star clusters known at the time. In 1895 and 1908,
he published supplements to the NGC, which he called the Index Catalogues (IC).
Nearly all of the bright, large, nearby non-stellar celestial objects have entries in
one of these three catalogues. Astronomers use the catalogue numbers to refer to
these objects, preceded by the catalogue acronyms, NGC and IC. For example, the
Andromeda galaxy is coded M31 in the Messier catalog and NGC 224 in the NGC
catalogue.
The Andromeda constellation (M-31/NGC-224) is the closest large spiral
galaxy to our own Milky Way. John Flamsteed (1646-1719), the first Astronomer
Royal, compiled his celestial atlas,
Atlas Coelestis
at Greenwish. His catalogue of
about 3,000 stars visible from Greenwich was published 10 years after his death
(1729, 1753). Figure
2.15
shows a Hubble Space Telescope (HST) photograph of
the Andromeda galaxy (left) alongside an Andromeda constellation figure from
Flamsteed's catalogue (right).
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