The 17th Century was something of a coming out party for science in general.
For the first time in the history of the world, physics, astronomy and much of
mathematics went from mythological musings to rigorous disciplines. Perhaps
most important for astronomy were the contributions of Galileo Galilei.
Galileo Galilei (1564-1642) is often credited for inventing the astronomical
telescope. Of course, he was simply one of the first to use the already
invented telescope observe the heavens. After hearing of the telescope, he
constructed his own three power version in 1609, and with that very primitive
instrument discerned for the first time craters and mountains on the moon.
That Galileo recognized such features (anyone can see the crater Tycho with his
naked eye) should hardly be a surprise, but it was only the beginning of the
uproar Galileo caused with the Catholic Church, which believed in a strictly
Ptolemaic viewpoint that all of the heavenly bodies were perfect, featureless
crystal spheres, and that the earth was the center of the Universe. It really
is hard to understand how one can look at the moon, with its many dark maria,
which form "the man in the moon," and regard it as a perfect crystal sphere,
but recall that this was in the same socio-political climate which apparently
allowed for very few records of comets or even the spectacular Crab Supernova
in 1054, which was so bright it was visible in the day for weeks.
Undaunted, Galileo by April of 1610, had observed the phases of Venus, moons of
Jupiter and spots on the Sun, which he published in his pamphlet, "The Starry
Messenger." All of these phenomena flew in the face of the Ptolemaic view of
the Universe. First, sunspots are both imperfect, and are transient---as the
sun rotates, they move across the disc of the sun; also they wax and wane on a
timescale of days to weeks. The Ptolemaic believed that all heavenly bodies
were "immutable," and sunspots certainly are not that. Second, Galileo
observed that Jupiter appeared to have its very own planets (now called the
Galilean satellites), which destroyed the notion that all heavenly bodies orbit
the earth. Last, the phases of Venus could only be explained if the sun were
at the center of the "Universe," as shown below.
|
| The phases of Venus, explained only by having the sun at the
center of the Solar System. (R. Martin, UIUC)
|
So, Galileo had disproven, by any scientific standard, the Ptolemaic (and
Catholic) mythology of the heavens.
The church obviously disapproved of Galileo's findings, but for the twenty or
