So what is astronomy? The word comes from the Greeks themselves.
ἄστον meaning 'star', and νομος, meaning 'law', form the word 'astronomy' literally meaning 'the law of the stars.'
Why were the Greeks so captivated by astronomy?  Like you and me the
Greeks looked up and questioned
why the planets wandered and the sun rose.
Alexander the Great helped to quench this thirst for knowledge when he conquered Persia
in 331 BCE, which placed Greece in the
midst of Mesopotamian and Zoroastrian
observations and theories. The country's
extensive trade routes provided further
knowledge from the Indian Vedas and
Chinese astronomers. We have some of these
theories written down, but most of the surviving writings before 450BCE are comments from Aristotle
about theories he would like to
criticise. How nice of him!   Who were these great minds?
Pythagoras was one of them. Credited as the first Greek to think the Earth spherical, antedating Columbus 
about by over two thousand years , the
Pythagoreans concluded that the Earth's shadow on the Moon hinted the curvature of our planet. Most Greeks astronomers believed that the earth
centred the universe however, there were many indicators
that this was incorrect such as the
ever varying brightness of the planets. Anticipating Copernicus and Galileo by almost twenty
centuries, Aristarchus of Samos was the first to suggest that the Sun, rather than the Earth
was the center of the universe
and that the rest of the planets orbited
it. He also realized that the Sun was
a star and the universe was much larger
than previously believed.  However Aristarchus
was trapped with a good idea in a bad time. Nearly all Greek astronomers assumed that the
universe was a sign of perfection and all celestial bodies had a circular orbit.
Aristarchus' measurements meant that the orbits of the planets would have to be elliptical
rather than circular, and although we now know that they are in fact elliptical
This viewpoint was considered sacrilege.  Our next genius lies in the brain of Hipparchus
of Nicea, the most renowned Greek astronomer in his time. His resume including having
calculated with an error of less than
one second, the length of the lunar month
and having estimated the solar year
with an error of just six minutes. He even
managed to catalogue the precise
latitude and longitude of 1080 stars.
However, Hipparchus made a mistake; a
big one - by supporting the wrong thesis.
Being the most powerful and influential
mind at the time, he ended Aristarchus'
correct
sun centred theory. Although Hipparchus'
earlier accomplishments were ahead of
his time, his belief in the Earth
entered model may have dragged
astronomical progress backwards. 
Consequently, Ptolemy, in an essay which would
remain the primary text for a thousand
years to come, began to
design ever more complex diagrams to
account for the errors that came with the
Earth centred model. He added epicycles,
circles, upon circles upon circles, further and further from the truth.  So a blessing or a curse?
The Ancient Greeks made incredibly
accurate measurements such as the
circumference of the Earth without modern technology and attempted to steer away
from the idea that the gods controlled the
heavens. Their theories revolutionised science and
triggered the beginnings of an astronomical age that continues to this day. However
the Earth centred model, supported by Hipparchus persisted for another 15 centuries,
guiding some of the brightest minds in
history down the wrong path.
But that is the risk that bounds every genius,  two sides of the same coin, when they are
right- they can trigger a revolution of
knowledge, but when they are wrong -
they can freeze it for centuries.
 
 
 
