Video Transcript: Galileo

Well, all of this all got mixed up and changed with the invention of the telescope.  Once the telescope came along, there was an opportunity to make a whole new set of observations.  And these new observations could perhaps prove once and for all, whether the Earth was at the center of our solar system, or whether the Sun was at the center of our solar system.  When we talk about the telescope, we have to start by talking about Galileo.  Galileo is not the inventor of the telescope but in many ways, he is the father and founder of modern astronomy because Galileo was the first person to take the telescope, and make his own and look at the night sky with it.  More than just observe the night sky, he also recorded his observations and that's an important part of the process of science, is that we record what we're observing day after day and night after night and we look for patterns.  Because Galileo was the first one to do this, he made all sorts of discoveries.  He was the first person to ever see spots on the Sun, to see mountains on the Moon, and to see planets, I'm sorry, moons orbiting around the planet Jupiter.

What's really cool is we can actually see his own notes; these have been saved over time.  So these are his first observations of the moons around Jupiter.  Each of these little stars is one of the moons that he could see in his little telescope and from night to night, he observed that these moons were in different places relative to Jupiter.  And he eventually deduced that these were actually moons orbiting around Jupiter.  Now, this isn't proof that the Sun is at the center of our solar system, it did suggest to Galileo that, wow, the Earth must not be the center because here these moons, they aren't going around the Earth, they're going around Jupiter.  So some things are orbiting Jupiter, not the Earth.

Now the real proof that our Sun is at the center and that the Earth is orbiting it came from an idea that wasn't Galileo's original idea, but it was someone wrote him a letter.  They said, Galileo, I understand you have this telescope, you've been making observations.  I wonder if you've ever looked at the phases of Venus.  Okay, so just like the Moon has phases, the planet Venus also exhibits a series of phases like crescent and gibbous and all those things.  And this letter, the gentleman, he suggested, these phases of Venus could indicate whether the Sun is at the center of our solar system, or whether the Earth is at the center of our solar system.  So here was the first opportunity where a real observation could be made that could definitively answer this question.  Now let's take a minute and try to understand how the phases of Venus connect to this question of whether the Sun is at the center or the Earth is at the center.  

So this is the third picture in our gallery.  And it's a complicated diagram, but we can make sense out of it.  On the left hand side, you see a geocentric model.  Alright, in the geocentric model, Venus goes around in an epicycle as it orbits the Earth, and the Sun is also orbiting around the Earth.  Now, if we look at the very top, what it shows is the phases we would expect to see from Venus.  Now, if you recall, crescent phases occur anytime an object is between the Earth and the Sun.  Those are always the crescent phases.  And in a geocentric model, Venus would always be between the Earth and the Sun.  So the only phases we would ever see for Venus would be crescent phases.  Gibbous phases can occur when Venus would be on the opposite side of the Sun.  So on the right hand side of this picture, we see what the heliocentric model would be, that is, Venus and Earth both orbit around the Sun.  And that case, we can see that Venus at certain points in its orbit would be on the opposite side of the Sun as the Earth and during those times, we would actually be able to see a gibbous of Venus and possibly even like a full Venus in addition to the crescent phases.  So this very simple idea, which is if you can observe Venus with a telescope, if you ever, of course, you will see crescent phases, we know you'll always see crescent, both models suggest that, but if you ever see a gibbous phase for Venus, where it's more than half illuminated, then you know that, at a minimum, Venus must orbit the Sun and if Venus orbits the Sun then really all the planets, including the Earth, orbit, the Sun. 

So think about this.  This is incredible.  With a single observation, if you were to go out at the right night with your telescope, and you looked at Venus, even for two minutes, ten seconds, and you looked at Venus and you saw it's a gibbous phase, you could answer this question.  That is incredible.  It's astounding.  In ten seconds, Galileo could answer this question with a telescope if it's the right night.  This points to something that I think is amazing about astronomy and about God.  

God has made it possible for us to answer these questions.  I mean, this question of does the Earth orbit the Sun or does the Sun orbit the Earth, that could have just been impossible to answer.  Maybe there's no observation that could ever be made.  Maybe telescopes aren't possible; they're impossible to make; whatever.  But across the board this is just one example.  We'll see it time and time again.  God has crafted a universe where it is possible to answer these kinds of questions, where it's possible to understand how our universe is organized.  The way I like to think of it is God didn't have to do it like that.  He didn't have to make it possible but He must want us to do this kind of exploration.  He must want us to learn more about how the world works. That's something that He's hardwired not only into the universe, but He's hardwired into us to the desire to be able to understand this universe that He's made.  This is such an amazing example that a single observation answers this question.  

Well, Galileo was like, well, that's an awesome idea.  I hadn't thought of that.  And so he goes, and he makes this observation.  And this is actually the recording in his notebook of the observations that he made - crescent phase, crescent phase, a quarter phase, and a gibbous phase.  And so Galileo makes the observations.  He sees once and for all.  Venus exhibits phases.  It must orbit the Sun, and so the Earth must orbit the Sun.  

Now, there's a lot of other things happening in science at the time.  You know, this is around the time, you know, Newton had been putting ideas in physics which helped make sense out of how the Earth could be moving so fast and yet we feel like we're stationary.  Galileo was familiar with these ideas; he contributed to some of these ideas as well.  So all these things work together to say, wow, maybe the Earth is moving incredibly fast, and rotating incredibly fast and that the Sun is what's stationary at the center of our solar system.  But this observation was critical.  It remains.  Well, there's one other kind of observation really, well, there's a few now because of modern technology, but really for hundreds of years this was the only observation which was conclusive proof that the Earth was orbiting the Sun.

Galileo is famous for something else.  Galileo is famous for being tried as a heretic by the Catholic Church.  So when Galileo made these observations and became convinced that the Earth was not the center of the solar system, he couldn't help but share these ideas.  These were a big deal to him and to other people.  And the Catholic Church, much like the case of Copernicus, felt like these teachings went against the teachings of the Church and against the teachings of the Bible.  And so they told Galileo, you can't discuss this.  I mean, you can talk about these mathematical ideas, but really to suggest that that the Sun is the center of our solar system goes against the teaching of the Bible and is a heresy.  Well, Galileo couldn't bite his tongue.  All right, he wrote a book in which he had two characters and he kind of tried to follow the letter of the law, while skirting around what the Catholic church asked him to do. He wrote a book where there's two characters debating the geocentric versus the heliocentric model. And the character who was defending the geocentric model, which is the church's official stance, he called that character, like Sim… Simplitico, or something like that, basically, like idiot, all right.  And he, he had that person basically being the fool in his story.  And then the other character was the one making the case that Galileo was making.  

As you might expect, this really upset the people in the church because, in a sense, the character, this Simplitico character was, in a sense, a dig at the pope at the time.  And so in many ways, there's a lot of ways to read what happened to Galileo.  He was put on trial, he was convicted of these teachings told not to teach them anymore, put on house arrest for the rest of his life, and only pardoned, like 20 years ago in like the 1990s, or something like that.  So he had a pretty negative experience, because he made these observations and put forward these ideas.  Now, none of us today would think that his ideas were that controversial, right?  

So how do we make sense out of this?  A couple of things.  We've kind of talked about the time in which this happened. The inquisitions that were going on and trying to cleanse out any heresies out of the church.  The other thing to make sense out of this a little bit is Galileo's personality.  He was a tough person.  He had a tough personality, was kind of argumentative.  The way he wrote the book was certainly insulting to the church at the time.  But what's interesting to me is the way this story is told by secular scientists today.  Oftentimes, this story is meant to illustrate our modern division between the church and science or between Christianity and science with faith and science.  And this is a way of, kind of presented by secular scientists as a way of saying, look, the church is closed minded, you know, they interpret the Bible in a particular way, which ignores all of science, and they're only going to, you know, push scientists to the side and, and see what they did to Galileo. That's what the church is like.

And well, that's what happened at that time. And, you know, I think the context makes a little more sense out of what happened then, not to excuse what happened but what is tremendously exciting to me is the opportunity that we have, as Christians, to see what science has discovered about our universe and to put that together with what we know about God as He's revealed to us through Jesus Christ, and through His Holy Scriptures.  And when we put those together, we have this just like, power that is unbelievable. The secular scientists only have half the story; it’s not even half the story.  They have 10% of the story.   But when you put it together with what we have it's this beautiful, amazing picture of the God that we love and who loves us.

And so, I think that the heart of the story of Galileo, the heart of this story is that we have to think about not only how we interpret the universe and how we make sense of the observations of the universe, but we really have to reconcile those observations with what we know and how we interpret the Bible.  The Bible teaches us, you know, there's a famous saying that is associated to Galileo, which was, the Bible teaches us how to go to heaven not how the heavens go.  All right, and I don't agree with that. I don't really agree with that sentiment but what's important to realize is this - what if, when God in his infinite wisdom, said to Moses who was writing those early two chapters of the Bible, what if He said, “I'm going to reveal to Moses and to everyone who ever reads the scriptures, I'm going to reveal the precise details of how I created the universe.  And all these subtle details.”  What if He chose to reveal all of those details, that the Sun is at the center of our solar system? That the Earth orbits in this particular way that these galaxies are like this?  And that the universe is this shape, or has these different features?  What if He wanted to reveal… is that really what He was trying to do in his revelations throughout scriptures?  No, I don't think that was… that’s not the purpose of scriptures.  That's really not the purpose.  And besides, God has written that in the heavens, so we can still read it, we can still figure it out.  

So there's this beautiful thing with special revelation and general revelation, and they both are telling us about God.  And I think what we see at the time of Galileo is that the church wasn't fully appreciating the value of general revelation.  And that's what I think is our advantage.  And your advantage by taking this course, is my hope is that you come away from this course more than anything else, with an appreciation of what God is revealing through general revelation.  Is it as important as the Bible was revealing through special revelation?  No, it's not.  It's not as important.  But is it powerful?  And doesn't it help us get a bigger picture of God?  Yeah, I think it does.  And so, to me, that's what the story of Galileo is telling, and why it's important for us to reflect on this trial that Galileo went through, in addition to the profound astronomical discoveries that he made.  

All right, sounds good.  We'll see you next time.