Galileo''s observations are the foundation of our basic understanding of the universe the sun, encircled by orbiting planets, is at the center, and not the Earth.
Before 1610, it was generally accepted that the universe was centered on the Earth, that God had made the Earth and made humans on it, and we were the center of everything.
After 1610, you have this empirical evidence that maybe the Copernican hypothesis of the sun being the center of the rotation of the universe is physically true.
Galileo''s drawings upended the world view that had lasted for at least two millennia.
In 1543, Polish astronomer Nicolaus Copernicus questioned the idea that the Earth was the center of the universe, but couldn''t provide proof.
The universe was changing and this book was the agent of that change.
It has a kind of deeper psychological impact, I think, about where we are in the universe and what our whether we''re anything special.
It starts to shift humanity from its central, God-given position physically at the center of the universe, to a more marginal position where we are third rock from the sun, hurtling through space.
It opens up a whole load of new questions about what it means to be human.
After observing the moon, Galileo shifted the telescope and was able to see Jupiter.
'On the 13th of January, four stars were seen by me for the first time, in this situation relative to Jupiter: Three were westerly, and one was to the east.
They formed a straight line except that the middle western star departed slightly toward the north.'
'On the 14th, the weather was cloudy.'
'On the 27th of February, four minutes after the first hour, the stars appeared in this configuration: The easternmost was ten minutes from Jupiter; the next, thirty seconds.'
Galileo had seen three of Jupiter''s four largest moons, effectively proving the Earth was not the center of the universe.
He realized that the implication of that was that they were rotating around Jupiter, and nobody's conception of the solar system or the universe in general had ever allowed that planets have smaller bodies revolving around them.
When it came to the moons of Jupiter, there was just no precedent for explaining it.
And he's open about his amazement, his befuddlement at first, how to make sense It takes a couple of days for him to come to, Wait a minute.
There''re bodies moving around Jupiter.
There's no other explanation.
His observations, of both Jupiter''s satellites and the imperfect surface of the moon, would ultimately contradict Church teaching.
In 1616, six years after Sidereus Nuncius was published, the Roman Inquisition banned heliocentrism the belief that the Earth revolves around the sun from being taught.