GENERAL ASTRONOMY ARTICLES
SOUTHERN ASTRONOMICAL DELIGHTS
AN INTRODUCTORY PERSPECTIVE
By Andrew James
“Astronomy surpasses every
other science in the sublimity
and grandeur of the objects in which it contemplates.
The magnificent appearance of the Celestial Bodies, the
regularity and harmony of their motions, combined with
the various phenomena they display, strike us with
astonishment and profound
admiration!”
“The British Celestial
Atlas”, vi. (1830)
G. Rubie
ASTRONOMY can be summarised as the study of all objects and
their structures lying beyond the confines of the Earth. The oldest
and perhaps the most fascinating of all the sciences, and it is
different than them as sky is accessible to everybody. Originally,
the science of astronomy was about understanding the movements and
positions of all celestial bodies. Today, with the introduction of
topics relating to the sciences of both biology, physics and
chemistry, means that astronomy now encompasses much wider courses of
study. Since the mid-19th century, the adopted method of
investigation into astronomy subdivides into; Astrophysics, applying
to the basic principals governing all bodies from planets, stars to
galaxies, and Cosmology, applying to the understanding nature of the
whole universe — accounting for all atomic matter, the stars
and galaxies; and towards details of the universe — its origin,
evolution and eventual demise. In the modern sense, the science of
astronomy generally encompasses both astrophysics and cosmology.
For many of us, astronomy great interest, probably has some real
psychology basis. The darkness at night awakens primitive instinct
deep within us, like children who often fear the night, which is
sometimes manifest by imagining fictitious unseen creatures. We
likely feeling this from the transition day into night, producing
effects like the lowering of the body’s
temperature or the loss of colour vision. This makes us seemingly
vulnerable and insecure — feelings which are both dark and
remorse. These fears haunt us, as they may also reminded us of the
unknown void of the subconscious that we daily explore in our nightly
sleep.
Yet the darkened night sky is gloriously blanketed with stars,
that each endowing us with the true sense of company. Those many tiny
points of illumination, continue to ignite some inner flame within
us. Once they have touched you, and you will have come to know their
nightly positions, then their daily appearance becomes more akin to
visits from old and familiar friends.
Over several nights one can see the changing phases of the Moon or
perhaps discern the slow movements of the planets among the
background stars.
Even the slow and steady rotation of the sky is of particular
interest. “New” stars will appear to rise from the eastern
horizon, while more familiar ones lay down to rest and disappear in
the west. We also discern that the star patterns, or constellations,
change as the weeks go by. Stars rising in the east, say at 10pm, are
found to rise almost half-an-hour earlier as each week progresses. At
the same instant, different stars closer to the western horizon will
gradually disappear. As the seasons change, so the whole aspects of
the sky changes. Those constellations once visible in the western
evening sky disappear altogether, only to be replaced by others from
the east. Summer in the southern hemisphere finds the constellation
Orion the Hunter dominating the sky, while during winter the
constellation of Scorpius shines gloriously overhead. Eventually
after one year has passed, the sky returns to its original places,
again showing us the same familiar constellations of that season.
Moving to the southern horizon, other constellations like the
Southern Cross do something different. These stars never set below
the horizon and so can be seen throughout the year. If we could see
the stars during the daytime, we would see the Southern Cross, the
constellation known as Crux, travels in nearly one complete circle in
enty-four hours. As the seasons pass in places like Sydney, Australia,
at 10pm during summer finds the Southern Cross fairly close to the
southeastern horizon. By autumn at the same time, we see the Cross
hanging high up and slightly south of zenith. Similarly, winter finds
the Cross facing southwest, while during spring it will be pointing
downward towards due south. If we were in the northern hemisphere,
similar observations occur, except now we have to face the north and
look at the “mirror” constellation named Cassiopeia, sometimes
nicknamed the chair. Due to their positions in the sky, neither the
Cassiopeia can be seen in the southern sky nor the Southern Cross
from the northern one.
On dark nights, away from the city lights, we can see dividing the
sky into two hemispheres the pearly white light known as the Milky
Way. City dwellers often miss seeing the Milky Way, but in the
country, the sky blazes splendidly with its beautiful pearly light.
Looking with the smallest of telescopes reveals that its faint
unresolved light is really seemingly uncountable multitudes of stars.
These stars are in our own Galaxy. More humbling is to think that our
own Sun is only the tiniest part in these myriads of stars, whose
total number of stars exceed four-hundred-billion. The poet Milton
aptly describes this in the classic “Paradise Lost”:–
“…as stars to thee
appear Seen in a galaxy, that Milky Way
Which nightly as a circling zone thou seest,
Powder’d with stars.”
Our entire lives are also all “in-tune” with the skies. We set our
daily habits to the rising and setting of the sun, and often
unbeknown to us, have our internal biological clocks and sleeping
habits set to its daily movements. The moon controls many human an
many non-human reproductive and biological mechanisms. A woman’s monthly cycle, for example, exactly mimics
the lunar cycle, while once each Full Moon, some fish species and
coral will spawn simultaneously together in the sea. Similarly as the
sun is about to rise, electrical activity increases in all our
bodies, telling our brain of the eminent sunrise and to begin our
daily activities. Another is the honey bees, which use the
ultra-violet polarised light of the sun to find their orientation and
the direction of the hive. Even some birds are thought to during the
night to use the bright stars to navigate across the sea or land to
travel to their yearly migratory destinations.
Our own moon, and lesser in extent, the sun, also influence the
tides. This twice-daily cycle is completed once every twelve and half
hours or so. The feeding habits of fish in the sea know of the tidal
cycle, and use this to take advantage of the minions they feed for
sustenance.
Astronomy, in a different way, poses many questions about our own
role and place in the Universe. These have profound implications on
the human mind and our personal existence. For some it extends to a
strong religious faith, firm beliefs or through dogma, and may be
based on a priori − either as scientific or perhaps some
philosophic view or perspective. Many of these questions have greatly
perplexed many great thinkers in the past. This will likely continue
in the future. We find most difficult, for example, that the vast
astronomical distances or the true size or mass of most astronomical
objects to be absolutely astonishing. Our feeble minds begin to show
some weakness, for we cannot grasp such immensities.
Harder for each of us is to realize that we are both looking into
space and observing backwards in time. Reasons for this is that light
travels no faster than an absolute finite speed of
three-hundred-thousand kilometres every second. The distance of
three-hundred-thousand kilometres travelled is equal to about
seven-and-a-half times around the Earth’s circumference. Even at this speed, it
takes sunlight about eight minutes to cross the distance of
one-hundred-and-fifty million kilometres between the Sun and the
Earth. To the nearest star Alpha Centauri, even at this colossal
velocity, it takes over 4.3 years to reach our eyes. If something
were to happen to this star right now, we will only know about it 4.3
years after the event sometime in our future. So if any event happens
with any other astronomical object, knowing about it will only
dependant on how far the object is away in light-years from the
Earth.
A plentiful abundance exists of true wonders in our Universe. To
see them requires only small telescopes or binoculars. Examples of
these commonly existing types of these diverse astronomical objects
include;
Double and multiple stars Stars connected
physically by gravitation, orbiting each other in tens to thousands
of years.
Variable stars Stars that vary in
brightness over minutes, years or sometimes centuries.
Open star clusters and Globular star
clusters Stellar groups containing many hundreds to several
millions of stars within several tens or hundreds of light-years.
Nebulae Huge gas clouds composed of vast
quantities of Hydrogen, Helium and dusty material that are
manufacturing and nurturing brand-new stars.
Planetary nebulae Illumination of gas
ejections via superwinds from old dying stars.
Galaxies Biggest single collections of
objects in the Universe containing many billions of suns, whose
feeble light travels through space for perhaps millions or even
billions of years.
It is important to note, once you start exploring the sky, that
each amateur stargazer has unique perspectives of their world.
He or she has seen vast distances, and has travelled to far different
places than the Earth, and has even seen into the distant past.
Last Update : 5th December 2014
Southern Astronomical Delights ©
(2014)
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