We've Turned Starlink into a Planetary Barometer

Starlink has many downsides. The megaconstellation interferes with astronomy, pollutes the atmosphere with metallic re-entry debris, and has pushed Low Earth Orbit to the brink of the Kessler Syndrome.

On the other hand, it makes a terrific barometer.

Earth is absolutely surrounded by Starlink satellites. More than 11,000 of them are circling our planet right now. Without exception, they all skim the outermost layers of our atmosphere, and so they experience aerodynamic drag. Drag pulls them down, and they have to fight back with thrusters. This makes them ad hoc detectors of air pressure. Every day, we read those detectors and boil the result down to one number: the sink rate.