Watching satellites from the ground is a popular pastime among amateur astronomers. Typically, the ISS and Iridium satellites were widely used because their orbits and design make them appear sufficiently bright in the sky. More recently SpaceX's mass launches of Starlink satellites have attracted attention for the wrong reasons .
Starlink is a SpaceX project to provide Internet over satellite. Various techniques are used to keep latency and bandwidth low. It talks about cross-satellite laser communication, autonomous obstacle avoidance and special constructions for limiting the amount of space debris generated. We covered the technology earlier this year in a comprehensive article.
The Starlink ships have long been concerned about astronomers relying on their work for a dark and unobstructed view of the sky. There are now a large number of satellites in relatively low orbits, and the vehicles have a high albedo, meaning that they reflect a significant portion of the sunlight that hits them. Since the vehicle also ran in a tightly packed train formation from the stack, there were already effects on the research operation.
There is hope that this problem will move to higher orbits when the vehicle is put into service will be reduced. SpaceX is also reportedly considering changes to the design to reduce the albedo and keep the astronomy community busy. Whether there are plans to launch 12,000 to 42,000 satellites, this is probably not the last time we have learned of this problem.