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Short answer: a lot. Long answer: a real lot… if you include the stars inside the Andromeda galaxy, which is also very visible from space as this recent time-lapse from the ISS shows!
The time-lapse comprises still photographs taken from the ISS on January 25, 2012, as it passed from over the Pacific Ocean southwest of Mexico to over Mississippi.
The video looks a bit grainy or noisy due to the relatively low level of light.
Still, many stars are clearly visible, as well as the hazy oval of Andromeda… one of the furthest objects visible with the naked eye. Over 2.5 million light-years away, we are seeing our neighboring spiral galaxy as it was when our human ancestors were first learning to use tools in the valleys of eastern Africa!
Now that light is shining into the windows of an extremely tool-filled Space Station… who knows what the light from today’s Andromeda will eventually fall upon in another 2.5 million years.
Video courtesy of the Image Science & Analysis Laboratory, NASA Johnson Space Center. Via the Gateway to Astronaut Photography of Earth.