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Comment by lpolovets | Hacker News Reader

How much light pollution will this actually create? I've read that SpaceX wants to launch 40k satellites that are 200 miles above earth. Each satellite is the size of a table. Could one see a table-sized satellite 200 miles away? Also given the surface area of the earth, the satellite density would be something like one every 50k square miles. How meaningful is that when it comes to light polution down at the surface of earth? How about for astronomers?

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The issue is for long exposure capture needed for quality astronomy. In that context any reflection from the sun on a satellite can trash any shot in an instant. SpaceX has tried to reduce the reflectivity of the Starlink sats but they still are a factor. Supposedly it was actually really bad at first.

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Does that actually affect real science, or is it just a matter of astophotographers wanting a nice picture without streaks? It's not like long exposures have to be done on film these days. Anomalous light sources can be removed in software.

I think if this is affecting basic science it's a real concern, but if it's just a matter of making long exposures of galaxies and nebulas less pretty then I have a hard time being overly concerned about it.

> Could one see a table-sized satellite 200 miles away?

We could see many of them with just eyesight when they first went up. Proper instruments are definitely going to pick that up.

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