Atmosphere of Earth sublimated into polar-mesospheric noctilucent clouds. These are the highest clouds in the atmosphere and may be visible to the naked eye if sunlight reflects off them about an hour or two after sunset or a similar length of time before sunrise. They are most readily visible when the Sun is around 4 to 16 degrees below the horizon. Lightning-induced discharges known as transient luminous events (TLEs) occasionally form in the mesosphere above tropospheric thunderclouds. The mesosphere is also the layer where most meteors burn up upon atmospheric entrance. It is too high above Earth to be accessible to jet-powered aircraft
Opus: The Day We Found Earth their planet of origin to live among the stars. By then, Earth has become a mythical planet and the belief in its existence has become a religion called "Earthology". On the other hand, the human gene pool has deteriorated after millennia of genetic engineering, and the only way to revert this damage is to trace back to the oldest sample of genes left on their long forgotten home planet. Project Earth was then founded and a spaceship named OPUS was launched in order to search for Earth and save the failing human race. The story follows a childlike robot Emeth,