Instead, it's because the ISS used to orbit the Earth with its solar panels permanently pointing towards the Sun, since it was unable to change the panels' angle at the time.
In 2006, the station changed its attitude from a "solar inertial attitude" so that one side permanently remains pointed at Earth. Taking the same picture from the same angle would now result in "arcing trails," not sharp pinpoints, as Pettit explained.
During his six-month stay, Pettit took thousands of pictures of star trails, sharing them with the rest of the world on the internet.
And once there, he's planning to retake his recently shared image with the use of a nifty contraption.
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