Thread

Astronomer watches Starlink satellites sinking to build a 'planetary barometer'

67 points · 19 comments · whh

sandworm101 · 1790366324 · focus · HN ↗
The author seems to treat the atmosphere as a, well, sphere. It isnt. It is not of equal depth at all areas. As starlink (and every other sat) only travels in part of the atmosphere each day they cannot measure the entire atmosphere. So you measure a thousand starlinks to get an average. Ok, but a significant bulge on one side of the planet will slow all sats, giving the false impression of a homegenous trend. So you have to track very specific sats in very specific survey orbits... but also update that list as the orbital shell rotates around the earth. It is a very complex problem.
1. jjk166 · 1790373231 · focus · HN ↗
  > Ok, but a significant bulge on one side of the planet will slow all sats, giving the false impression of a homegenous trend.
  A bulge would not homogenously slow all satellites, each one would be slowed by a different amount depending on its particular path through the bulge. Those that pass through more of the bulge will be slowed to a greater extent than those passing briefly through. Satellites in different orbits tell you where the bulge is, satellites in the same orbit tell you how the bulge is moving.

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