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How do you know what the final orbits are? Why would they not be visible on the final orbits? Sure, only a fraction of the satellites will be above you and illu

by svara 6y ago

How do you know what the final orbits are? Why would they not be visible on the final orbits? Sure, only a fraction of the satellites will be above you and illuminated by the sun, but at 30000 that's still bound to be a huge number. See for example this guy who tried to model this for the lower number of 12000: https://twitter.com/Alex_Parker/status/1132335640605945856 https://twitter.com/Alex_Parker/status/1132335640605945856

modeless 6y ago
The final orbits are approved in advance by the government; there's no mystery. They are not visible to the naked eye in their final orbits because they are farther away and they maintain an orientation that allows their sunshade to reflect sunlight away from Earth instead of toward it.
- svara 6y ago
  There's actually a good primary source for this cited in the article [0], stating: "However, at low elevations near twilight at intermediate latitudes (45°–55°, e.g., much of Europe) hundreds of satellites may be visible at once to naked-eye observers at dark sites." This is referring to Starlink's 12000 satellite constellation, so thousands absolutely is the order of magnitude we're talking about when (if) they go to the planned 30000 and when other companies do the same. [0] https://iopscience.iop.org/article/10.3847/2041-8213/ab8016 https://iopscience.iop.org/article/10.3847/2041-8213/ab8016
  - modeless 6y ago
    That was before SpaceX added sunshades to Starlink, which reduces their brightness in their final orbits to below the threshold for naked eye visibility. https://www.spacex.com/updates/starlink-update-04-28-2020/ https://www.spacex.com/updates/starlink-update-04-28-2020/
  - valuearb 6y ago
    Only at dusk and dawn, and not when they have visors.
- olleromam91 6y ago
  That's good to know. Still, with tens of thousands of satellites planned (that's just SpaceX) and the need for them to de-orbit and then redeploy, I think there is going to be quite a few of these things visible at any given time.

by svara 6y ago

modeless 6y ago

The final orbits are approved in advance by the government; there's no mystery. They are not visible to the naked eye in their final orbits because they are farther away and they maintain an orientation that allows their sunshade to reflect sunlight away from Earth instead of toward it.

svara 6y ago
There's actually a good primary source for this cited in the article [0], stating: "However, at low elevations near twilight at intermediate latitudes (45°–55°, e.g., much of Europe) hundreds of satellites may be visible at once to naked-eye observers at dark sites." This is referring to Starlink's 12000 satellite constellation, so thousands absolutely is the order of magnitude we're talking about when (if) they go to the planned 30000 and when other companies do the same. [0] https://iopscience.iop.org/article/10.3847/2041-8213/ab8016 https://iopscience.iop.org/article/10.3847/2041-8213/ab8016
- modeless 6y ago
  That was before SpaceX added sunshades to Starlink, which reduces their brightness in their final orbits to below the threshold for naked eye visibility. https://www.spacex.com/updates/starlink-update-04-28-2020/ https://www.spacex.com/updates/starlink-update-04-28-2020/
- valuearb 6y ago
  Only at dusk and dawn, and not when they have visors.
olleromam91 6y ago
That's good to know. Still, with tens of thousands of satellites planned (that's just SpaceX) and the need for them to de-orbit and then redeploy, I think there is going to be quite a few of these things visible at any given time.