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
Where Do We Come From? What Are We? Where Are We Going? Where Do We Come From? What Are We? Where Are We Going? Where Do We Come From? What Are We? Where Are We Going? is a painting by French artist Paul Gauguin. Gauguin inscribed the original French title in the upper left corner: D'où Venons Nous / Que Sommes Nous / Où Allons Nous. The inscription the artist wrote on his canvas has no question mark, no dash, and all words are capitalized. In the upper right corner he signed and dated the painting: "P. Gauguin / 1897". The painting was created in Tahiti, and is in the Museum of