"The reason we have the stars twinkle at night is because the light is being kind of blurred by the atmosphere around the Earth. That is why the Hubble Space Telescope is so good, because it is above the atmosphere. So it is kind of like looking at the sun from the bottom of a swimming pool, versus looking at the sun above the swimming pool."

Source : "NASA Astronaut Discusses Gravity and the Dangers of Spacewalking". Interview with Alejandro Rojas, www.huffingtonpost.com. October 3, 2013.

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