Chris Hadfield. He is an educator in the truest sense of the word. During his time on the International Space Station, Hadfield went out of the way to engage the public. He showed us what happens when you cry in space, how difficult it is to ring out a washcloth (and get it wet to begin with), how awkward it is to get sick in space, and the various difficulties that arise what you are forced to use the bathroom without gravity.
More than that, he showed us our world anew.
Hadfield regularly posted images of the Earth from the ISS. He even took requests, zeroing in on our most cherished places and showing us what they look like when you are 220 miles (350km) above the surface of the Earth. Here, he talks about what it was like to see our world from space.