Jim Nash writes in Scientific American:

Earlier this year Iran’s defenseminister put the world on notice: His nation had developed the ability to “easily” watch spacewalking astronauts from the ground. The announcement was largely ignored, in part because it made the minister sound like a James Bond villain. The boast was also a bit anticlimactic, given that even amateur astronomers are already recording in detail what happens in low Earth orbit.

Both the technology involved and the techniques used to observe satellites and even the occasional astronaut perched outside the International Space Station (ISS) are improving, much to the presumed chagrin of governments looking to keep certain on orbital activity confidential.

In a development harkening back to the earliest days of desktop computing, highly skilled stargazers are hacking together optics, electronics and software to create sophisticated observatories of their own. In fact, one French astrophotographer, Emmanuel Rietsch, has begun selling software and hardware that…