Title: Minding the Heavens – The Story of Our Discovery of the Milky Way
Author: Leila Belkora
Publisher: Institute of Physics Publishing,
2003 (First)
ISBN: 978-0-7503-0730-7
Pages: 369
Anyone looking up
at a very dark night sky would fail to be mesmerized by the panoply of the
celestial sheet of stars adorning, as it seems, the roof of the sky. Stars have
been providing unending inspiration to many young ones to identify their future
career in science. Most people are aware of what stars are, how they form and
die, why they are being at their present locations and take for granted the painstaking
research and study that went behind our present knowledge of the stellar
systems. Leila Belkora puts up a brilliant effort to narrate the history of our
understanding of the Milky Way, our parent galaxy. Ask any school student and
he will answer that we belong to the Milky Way, but we must read this book to
understand the story of the quest that finally culminated in getting us to the
point where we are now. The book does not merely describe the discoveries as
such, but proceeds to make the reader conversant with the socio-political
background and the personal lives of the astronomers who made the breakthrough.
The book is so structured and lucid as to make it readable like a work of
fiction. And the author is a renowned scholar, dividing her time between
science writing and teaching astronomy at the University of Colorado, Boulder.
It is said that every well begun job is half
done. Belkora does a wonderful job in laying out the preliminaries with a good
introduction and a thorough discourse on the general concepts of astronomy and
its history – how the pieces nicely fell in to the pattern. The narrative is
concise and the economy of words gives it added significance as a prelude to
the subject matter. The author answers a recurring question in the minds of
students of astronomy, that of why many of the stars possess Arabic sounding
names. The answer is curious to know. First work on naming and categorization
of stars based on the luminosity was taken up by Hipparchus of Greece in second
century BCE. This was compiled and published by Ptolemy of Alexandria as
‘Almagest’. However, great tribulations were taking place in the near east
during the first few centuries of Common Era. Then came the onset of dark ages
and learning took a back seat. The mantle of scientific enquiry shifted to
Baghdad which held it high for nearly four centuries. A renowned astronomer, al
Sufi published a treatise in Arabic around 900 CE which was translated to many
European languages in the Middle Ages and found their entry into modern lore.
Europe continued to hold on to the concepts originated
by Ptolemy and Hipparchus even during the times of Newton. The suns, stars and planets
were thought to be moving along three-dimensional, concentric spheres around
the Earth. The celestial spheres were thought to be put in motion by God. The
first stirring in the right direction was taken by Thomas Wright in the 18th
century. Even though a theologian and philosopher, Wright first suggested that
the Milky Way is seen as a stream because we might be looking at it edge on. Wright
published his observations and results, but didn’t gain much credence due to
his metaphysical and religious arguments that crept into the subject matter. But
his ideas were noted by William Herschel, A German by birth, but naturalized in
England. Herschel, working with his siblings, was instrumental in discovering a
new planet, Uranus. This discovery was the first of a planet since recorded
history. A musician-turned–astronomer, his fame lay in building optical
telescopes himself and using them to estimate the distances at which stars are separated
from us. A consensus had dawned among the astronomers that the huge distances
of stars could be measured by accurately finding the parallax of stars – the
apparent shifting in position of a star caused by the Earth’s movement around
the sun and taken at diametrically opposite points in the orbit, say in June
and December and situated 300 million km apart. Unfortunately, Herschel’s
results were in error.
In any field of study it is not unusual for
an idea to get stagnated for a while for want of instruments of sufficiently
advanced technology to verify its predictions. Belkora establishes that this
was true in the case of measuring stellar parallax also. It fell to the lot of
Wilhelm Struve and William Huggins to compile these figures of a vast numbers of
stars. At the same time, the author identifies the transition that was taking
place in astronomy in early 20th century. Up to that period, Europe
led the field in the form of excellent observatories equipped with instruments
that were in league of the world’s largest. Americans didn’t even have a decent
telescope till the 1830s, as exemplified in the lament of John Quincy Adams, President
of the US at that time. But with the immense progress that was lifting America
from the clutches of primitive technology, lots of new observatories began to
spring up across university towns and some of them rivaled competing
installations anywhere in the world. Harlow Shapley was a senior figure among
the American astronomers.
Belkora implies that the confirmative
evidence of the structure of the universe came with the work of Edwin Hubble,
who is also the most famous astronomer of the last century and known
eponymously with the space telescope that is still working wonders in a Near
Earth orbit. Till Hubble’s time, the scientific community was divided on the
question of whether the Milky Way was the only galaxy or it was only one among millions.
The three-dimensional space is viewed through the two-dimensional sky and distances
to various stars could be deduced only through ingenious schemes. Hubble
established that the immense distances which separate us from some of the
observed stars imply that they are too far away from the regions bounded by our
own galaxy. But one of his other observations caused a paradigm shift on the
theories on the origin of the universe. Hubble saw that galaxies are receding
away from us. The more distant they are, the faster they are moving apart. This
means that the universe as a whole was expanding. And it also suggested that
there was a time when the expansion began from a point in space-time,
euphemistically called the ‘Primordial Atom’. See how quickly Hubble’s
discovery paved the way for concepts of Big Bang to take the centre stage.
Belkora
attempts to teach even the most ignorant reader some of the fundamentals of
astronomy. The collection of finely illustrated diagrams and the richly
detailed colour and monochrome plates prove their assertion. She does not
resort to go after a difficult argument without introducing it at a prior
occasion, so that the readers would be in sync with their ideas. The books
became endearing to all classes of people precisely because of the apparent effort
taken by the author to clear up doubts on fundamentals.
The
book’s subtitle says that it is a story of our discovery of the Milky Way. But
this description would be a case of underestimating the utility of the book. Belkora
not just stops at the Milky Way, the attempt continues forward to cover the
entire history of astronomy for two centuries beginning from the 1730s. Readers
should not get confused by the humility of the subtitle, the book’s scope far
outgrows our own galaxy.
Being
a scholar of astronomy, the author presents the arguments in a well balanced
way. She has visited every region of the Milky Way, like its centre, where the
current consensus is that a black hole is lurking. It is rare to see such
comprehensive treatment in books of astronomy. At the same time, a cautionary
note is also sounded about the limited knowledge we still possess about the
star system as not to mistake knowledge of the foam of a braking wave with that
of the ocean.
The
book is highly recommended.
Rating:
3 Star
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