All sciences are making an advance, but Astronomy is moving at high
speed. Since the principles of this science were settled by Copernicus,
four hundred years ago, it has never had to beat a retreat. It is
rewritten not to correct material errors, but to incorporate new
discoveries.
At one time, Astronomy studied mostly tides, seasons, and telescopic
aspects of the planets; now these are only primary matters. Once it
considered stars as mere fixed points of light; now it studies them as
suns, determines their age, size, color, movements, chemical
constitution, and the revolution of their planets. Once it considered
space as empty; now it knows that every cubic inch of it quivers with
greater intensity of force than that which is visible in Niagara. Every
inch of surface that can be conceived of between suns is more wavetossed
than the ocean in a storm.
The invention of the telescope constituted one era in Astronomy; its
perfection in our day, another; and the discoveries of the spectroscope
a thirdno less important than either of the others. New discoveries
are made every day with the advancement of telescopes. The Hubble
space telescope has let man see further into the universe then ever
before. Astronomy and space science is an ever changing study, and
possibly the most exciting of the sciences. It is for one reason that this
book was written, to hopefully interest more people in the exciting
study of the universe around us.