The mesosphere was the layer of a planet's atmosphere directly above the stratosphere and directly below the thermosphere.
In 2370, Data reported that Boraal II's mesosphere had gone due to atmospheric dissipation during the final moments of the planet's life. (TNG: "Homeward")
| Structure and layers of an atmosphere |
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| Planetary: troposphere • stratosphere • thermosphere • exosphere ozone layer • ionosphere (D region • E region) • magnetosphere • mesosphere |
| Solar: photosphere • chromosphere • corona |