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More than a classic rock album that'll change your life, this classic space rock has a dark side that has mystified scientists for centuries.

Hosted by: Hank Green
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Our First Glimpse of the Dark Side of the Moon

Our Startling First Glimpse of the Far Side of the Moon

The Massive Chunk of Metal Hiding in the Moon

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[Hank] Though the sun may shine on the far side of the moon, it is dark to us. Gravity keeps one side of the moon forever facing us, leaving the other side a source of perpetual mystery. And that side that forever faces away from us has sparked a ton of scientific questions over the years. But the first two questions were probably something along the lines of "what does it look like?" and "how can we see it?" so here's Reid with the answers.

[Reid] The dark side of the moon: mysterious, intriguing. Why does it have so much lore associated with it? Maybe because it took three spacecrafts visiting before we had any idea what it looked like. So, here's how we finally got pictures of the dark side of the moon for the first time, and what it took to get those images back to Earth.

In October 1959, we got our first pictures of the dark side of the moon thanks to the former Soviet Union's Luna-3 spacecraft. It was the third spacecraft to go to the moon. So two missions were complete before we even tried to snap some pictures of its far side. And it wasn't an easy feat.

Luna-3 took pictures just like how we would take them on Earth back then, with a camera and film processing equipment. But the impressive part is that the spacecraft then sent those pictures to Earth using electrons.

First, a camera was mounted in the probe to take the original photos. The film had to be temperature and radiation resistant because of the unwelcoming environment of space. But this film, just like film on Earth, had to be developed, fixed, and dried. And all that processing happened automatically within the probe while it was still in space.

Then, six antenna mounted on the outside of the probe transmitted the images to Earth. They were similar to the antenna on old household tvs. 

A cathode ray, which is made of streams of electrons inside a vacuum tube, produced a bright light that shone through the developed film and onto a super sensitive detector called a photoelectric multiplier.

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