Dr. Brian Keating

A telescope. So a telescope that he used was a refracting telescope. Lenses like eyeglasses, two of them, one put at the far end called the objective. It's closer to the object. The other one, the eyepiece, close to your eye. And he was able to magnify things about three to 10 times pretty easily.

A telescope. So a telescope that he used was a refracting telescope. Lenses like eyeglasses, two of them, one put at the far end called the objective. It's closer to the object. The other one, the eyepiece, close to your eye. And he was able to magnify things about three to 10 times pretty easily.

Light travels at the fastest speed of any entity. Photons travel at roughly 300,000 kilometers per second, except when they go into a medium. That's what they travel in the vacuum of space or in a vacuum in my laboratory or whatever. But when they go into a medium that's transparent or translucent, they slow down. You can think of it as the light waves themselves.

Light travels at the fastest speed of any entity. Photons travel at roughly 300,000 kilometers per second, except when they go into a medium. That's what they travel in the vacuum of space or in a vacuum in my laboratory or whatever. But when they go into a medium that's transparent or translucent, they slow down. You can think of it as the light waves themselves.

Light travels at the fastest speed of any entity. Photons travel at roughly 300,000 kilometers per second, except when they go into a medium. That's what they travel in the vacuum of space or in a vacuum in my laboratory or whatever. But when they go into a medium that's transparent or translucent, they slow down. You can think of it as the light waves themselves.

Imagine light waves as rows of soldiers marching together. And then imagine that they're walking an angle to the beach here in Los Angeles. They're marching at an angle. The ones that encounter the water first, they start to slow down. The other ones keep moving at a fast speed. And then the whole beam of light, the whole beam of soldiers gets bent. That process is called refraction.

Imagine light waves as rows of soldiers marching together. And then imagine that they're walking an angle to the beach here in Los Angeles. They're marching at an angle. The ones that encounter the water first, they start to slow down. The other ones keep moving at a fast speed. And then the whole beam of light, the whole beam of soldiers gets bent. That process is called refraction.

Imagine light waves as rows of soldiers marching together. And then imagine that they're walking an angle to the beach here in Los Angeles. They're marching at an angle. The ones that encounter the water first, they start to slow down. The other ones keep moving at a fast speed. And then the whole beam of light, the whole beam of soldiers gets bent. That process is called refraction.

We can do it – well, this yerba mate is so delicious. We can't do it because it's got a little bit of –

We can do it – well, this yerba mate is so delicious. We can't do it because it's got a little bit of –

We can do it – well, this yerba mate is so delicious. We can't do it because it's got a little bit of –

Put a pencil in a clear glass of water, same phenomenon will happen. That's refraction. It's the bending of light by what's called a dielectric or just a medium that's transparent or translucent. And you can do that in a way that you shape the wave of light coming in that will be magnified. And that's in fact what a telescope does. Tele means distance, scope means viewer.

Put a pencil in a clear glass of water, same phenomenon will happen. That's refraction. It's the bending of light by what's called a dielectric or just a medium that's transparent or translucent. And you can do that in a way that you shape the wave of light coming in that will be magnified. And that's in fact what a telescope does. Tele means distance, scope means viewer.

Put a pencil in a clear glass of water, same phenomenon will happen. That's refraction. It's the bending of light by what's called a dielectric or just a medium that's transparent or translucent. And you can do that in a way that you shape the wave of light coming in that will be magnified. And that's in fact what a telescope does. Tele means distance, scope means viewer.

So a telescope really means distance viewer. A microscope means small thing viewer. And so this was kind of revolutionary to use it for scientific purposes. Galileo did other things. We just take these for granted. We got all these cool cameras here. These are all refracting telescopes. You can see the lens in one. You can see that it's on a tripod. Galileo invented the tripod.

So a telescope really means distance viewer. A microscope means small thing viewer. And so this was kind of revolutionary to use it for scientific purposes. Galileo did other things. We just take these for granted. We got all these cool cameras here. These are all refracting telescopes. You can see the lens in one. You can see that it's on a tripod. Galileo invented the tripod.

So a telescope really means distance viewer. A microscope means small thing viewer. And so this was kind of revolutionary to use it for scientific purposes. Galileo did other things. We just take these for granted. We got all these cool cameras here. These are all refracting telescopes. You can see the lens in one. You can see that it's on a tripod. Galileo invented the tripod.

We take these things for granted, but people didn't realize that.

We take these things for granted, but people didn't realize that.

We take these things for granted, but people didn't realize that.