alt Hacker NewsTheir brightness is a mixture of a lot of things, including the huge PV arrays and the angle they have with the sun when they cross the terminator between night and day.
Starlink have already put a lot of effort into their satellites being much less bright than most satellites, including tilting their PV away from earth during the terminator crossing, so from what I've read you'll mainly see them while they're being deployed and while de-orbiting.
(Part of my still-expanding draft blog post about space data centres is to work out how bright a million much larger objects would look. If they were in the orbit with the most sun, that's a terminator-following sun-synchronous orbit, which is maximum brightness).
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Would the “datacenter” satellites be much larger? I thought each of them was only going to carry a rack or a cabinet worth of GPUs?
I watch them come up over the horizon right after sunset. Only a couple specific trajectories are visible and they disappear pretty quick. Later on in to a clear night and after your eyes adjust to the darkness, you can find them all over the sky. They look like very faint stars speeding around. It's quite spectacular and hunting them makes for a fun activity with others while relaxing in a hot tub.