Relive the Discoveries of Galileo September 2014 | Page 3

The Durham Region Astronomical Association

Introduction

Galileo turned his hand
-built telescope to the

Moon and stars and made
discoveries that shook the
world. That the Moon had
craters, mountain ranges and
valleys meant it was not the
perfect sphere as everyone
thought. The moons Galileo
discovered in orbit around Jupiter challenged the
principle that everything in the heavens orbited only
Earth. These and other significant discoveries made
by Galileo with his small telescope brought an end
to the ancient teachings of the Greek and Roman
philosophers Aristotle and Ptolemy, and ushered in
a revolution in our understanding of the universe.
In so doing, Galileo gave us the modern scientific
method of testing theories with experimental
observation and objective analysis.
On these pages we will retrace five of Galileo’s
world-changing discoveries, and note how they
contributed to our understanding. We will not only
retrace them, but repeat them ourselves! Galileo

had a very simple small telescope made with low
quality glass, so the discoveries he made some 400
years ago are easy for us to repeat with almost any
telescope available today. For each of these
discoveries, instructions are provided to help you
repeat, and record within these pages, the same
observations Galileo made.
While reliving Galileo’s
observations, you can sense
the same thrill of discovery
he did. As you take note of
the moons of Jupiter, for
example, imagine being in
Galileo’s place and time.
Think of the astonishment he
must have felt as he realized
the importance of this
discovery, and how it would
upset widely-held beliefs and challenge authority.
Reliving these discoveries will introduce you to
astronomy, and launch you into a life-long interest
in the universe above.

The Life and Times of Galileo
Galileo Galilei was born on February 15, and a musket ball of 1 pound from the Leaning
1564 in Pisa – in what is now Italy – three days Tower of A