Despite enjoying the honors bestowed upon him by the Venetian Senate,
Galileo continued to negotiate for a new appointment in Florence,
where his former pupil, Prince Cosimo de Medici, had become Grand
Duke Cosimo II. When, in March 1610, he published his discovery
of the lunar surface and the moons of Jupiter in a Latin treatise
entitled Sidereus Nuncius, or "The Starry Messenger,"
he went so far as to dedicate the work to Cosimo, and even named
the newly discovered moons the "Medicean Stars," after the Medici
family. Galileo was soon rewarded for his efforts at wooing the
powerful family: in June of 1610, he gained appointment as "First
Mathematician of the University of Pisa, and First Mathematician
and Philosopher to the Grand Duke," as well as a sizable annual
salary, and exemption from the obligation to teach classes. He
abandoned Venice and Padua for Florence and Pisa without a backward
glance–ending his decade-long relationship with Marina Gambi, the
mother of his children for the sake of his ambition–and while there
was great rejoicing in Tuscany, the Venetians cursed his duplicity
and arrogance.
Galileo was arrogant, certainly, but
by the end of 1610 he seemed to have reason to be. Sidereus
Nuncius had gained fame as the wonder of Europe, as philosophers
and scientists marveled at the new vistas opened by Galileo's telescope,
and kings and princes clamored to have the Italian astronomer name
his ever-increasing discoveries after them. And the discoveries
kept coming. In July 1610, the scientist had glimpsed the rings
of Saturn–although he mistakenly believed them to prove Saturn's
existence as in fact three stars in a row, rather than a planet.
Then, in December of the same year, he found that Venus, like
the moon, went through phases; this provided key evidence for the
Copernican system, since it suggested the Venus orbited the sun
just as the moon orbited the earth. In April of 1611, Galileo
announced the existence of sunspots, confirming the observations
of a German astronomer, Johannes Fabricius, and then, by charting
them over a period of months, he concluded that the sun actually
rotated.
As Europe's intellectuals gaped, the Catholic Church
squirmed. They were long accustomed to the comforting ideas of
Aristotle and Ptolemy, which assumed a crystalline, unchanging
universe–a creation befitting an all-powerful God. The flux and
change that Galileo now revealed bespoke a more chaotic system,
a less-than-godly lack of organization. But for a time it seemed
that disagreement would not necessarily lead to condemnation.
Galileo made a triumphant journey to Rome in 1611, where he stayed
with the Jesuit astronomers, who confirmed his observations in
almost every particular. He received the blessing of Pope Paul
VI, and more importantly, one of the Pope's advisers actually agreed
to look through the telescope. This was Cardinal Robert Bellarmine:
a great intellectual, Bellarmine had friends in common with Galileo,
and had studied astronomy in his youth.
However, the cardinal had also crusaded ardently against
heresy, and sixteen years earlier had condemned the celebrated
Giordano Bruno to death for, among other heresies, preaching a
form of Copernican philosophy. Thus the support of this man encouraged Galileo
in his hope that the Church might come to recognize not only his
discoveries, but the world-view they hinted at–the heliocentric
(sun-centered) philosophy of the Copernican system.
For by this point, Galileo considered heliocentricity
as providing the only model that fit all his facts. Copernicus's
model, with Kepler's adjustments (which included changing the orbits
of the planets from circles to ellipses) not only made mathematical
sense, but it explained all of his new data. The
phases of Venus occurred because the sun lay between the earth
and Venus during part of the year; the surface of the moon suggested
that Earth was just one among many similar planets; the moons of
Jupiter implied that many other planets had satellites orbiting
them even as they themselves orbited the sun. The evidence convinced
Galileo, and in the two years after his 1611 journey to Rome, while
he occupied himself with continued observation of sunspots and non-
astronomical work on the properties of floating bodies, he began
to speak of the Copernican system as fact, not theory.
This was his critical–and dangerous–move. The Church,
and especially Bellarmine, could accept the Copernican system as
a hypothesis, but not as truth. As "fact," it would challenge
scripture, which referred to the sun "rising" and the earth as
"unmoving"–and besides, from their point of view, there was insufficient evidence
to consider the theory proven. Still, the debate remained muted
until 1615, and Galileo was busy with other matters, as he suffered
from a variety of intestinal ailments, squabbled with rivals in
Germany over who had first discovered sunspots (he claimed he had
preceded Fabricius), and published his "Treatise on Floating Bodies,"
which he sent to Bellarmine in Rome. The cardinal approved of
the treatise's assertions; indeed, the work, which dipped into
experimental physics in its discussion of how ice behaved in water,
received favorable reviews almost everywhere. Galileo had reached
a peak of fame as one of Europe's truly great minds.
