4 ms·
The orbital period of the ISS is 93 minutes, and it is under Earth-pointing control. That means that facing prograde (direction of travel), there will be 360° o
by 4gotunameagain 2y ago
The orbital period of the ISS is 93 minutes, and it is under Earth-pointing control. That means that facing prograde (direction of travel), there will be 360° of rotation in one orbital period.
To find the angle that the camera must rotate in 15 seconds:
15sec/93min * 360° ≈ 1°
- dylan604 2y agoThat's a lot of great information that doesn't come close to actually answering the question. How does that image betray anything you just said. In the example image, the background is clear while the earth is a motion blur. This is obvious of a long exposure image while showing the camera is moving to track the stars with the earth is in motion below it.
- 4gotunameagain 2y agoOkay, I will explain like you're 5. If you have seen any videos from LEO satellites, including the ISS, you would notice that any particular point on the ground moves very fast from the camera's point of view. In the photo presented on the post, you can see the tracks of man made light pollution - the bright light emanating from cities being smeared across the image plane. But you can see the start and the end of those tracks, and they are small. Which means you can gauge the relative position of a single point on the ground at the beginning and at the end of the exposure. And it hasn't moved much. Ergo, you can estimate that the exposure time is quite small. Let me know if that wasn't clear enough, I am not used to explaining things to this level.