The International Space Station happened to be passing by when I was out doing some astrophotography. It’s a very high-profile object because it’s a lot brighter than any stars (it’s light coming from the solar panels reflecting the sun at us), and it blazes across the sky at an amazing speed. This last point is made obvious by the fact that all the stars appear stationary in the photo1, while the ISS made a brilliant streak.
Also visible near the bottom of the picture are two low-flying aircraft. The one in the bottom left corner had blinking lights, which is why it appears as a series of dots in a line.
My astrophotograhy teacher once showed me a picture he got of the ISS where the fins of the solar panels were visible. To put into perspective how difficult this was, he explained it like this:
At it’s longest dimension, the ISS is only about 109m wide, which is roughly the size of the needle antenna on top of the CN Tower. It’s also orbits about 400 kilometres above the earth, which is roughly the distance from Ottawa to Toronto. So to capture the ISS in a telescope at that magnification is like being in Ottawa and pointing a telescope at Toronto and seeing the antenna on the CN Tower…as it’s moving at 8 kilometres per second. In American terms, this would be like standing with a telescope in Las Vegas and resolving the characters of the Hollywood sign in Los Angeles if it was moving at 17000mph.
- They do move, but at a wide focal length of 16mm the streaking is minimized. [↩]