Astronaut Don Pettit shows how to take long-exposure photos from the ISS

NASA astronaut Don Pettit created his ain instrumentality to assistance him instrumentality photos of the stars portion connected the International Space Station — and the results are beauteous impressive. In a Reddit thread spotted by Space.com, Pettit describes however helium brought a homemade prima tracker with him to space, allowing his camera to seizure long-exposure photos without the stars leaving immoderate trails behind.

Star trackers are designed to rotate with the Earth — oregon successful Pettit’s case, the ISS — to forestall distortion erstwhile taking pictures of the nighttime sky. One of Pettit’s photos, which you tin spot above, was a 15-second clip exposure. He says his tracker completes a rotation each 90 minutes to lucifer the ISS’s transportation rate. “Without this tracker, you tin not instrumentality photo[s] longer than 1/2 sec without prima blur owed to the complaint of orbital motion,” Pettit writes.

In a abstracted post, Pettit notes that aligning the tracker connected a moving level isn’t an casual task, adding that helium tin presently instrumentality up to 30-second exposures “without important prima motion.” Taking photos done the ISS’s windows besides presents different challenge. “Looking done 4 panes of glass, 2 of which are 30mm thick, astatine an space makes for immoderate distortion and comparative optically induced prima motion,” Pettit says.