An atmosphere (New Latin atmosphaera, created in the 17th century from Greek ἀτμός "vapor" and σφαῖρα "sphere") is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low. Some planets consist mainly of various gases, but only their outer layer is their atmosphere.
The term stellar atmosphere describes the outer region of a star, and typically includes the portion starting from the opaque photosphere outwards. Relatively low-temperature stars may form compound molecules in their outer atmosphere. Earth's atmosphere, which contains oxygen used by most organisms for respiration and carbon dioxide used by plants, algae and cyanobacteria for photosynthesis, also protects living organisms from genetic damage by solar ultraviolet radiation. Its current composition is the product of billions of years of biochemical modification of the paleoatmosphere by living organisms.
Famous quotes containing the word atmosphere:
“The base of all artistic genius is the power of conceiving humanity in a new, striking, rejoicing way, of putting a happy world of its own creation in place of the meaner world of common days, of generating around itself an atmosphere with a novel power of refraction, selecting, transforming, recombining the images it transmits, according to the choice of the imaginative intellect. In exercising this power, painting and poetry have a choice of subject almost unlimited.”
—Walter Pater (18391894)
“It is better to have your head in the clouds, and know where you are ... than to breathe the clearer atmosphere below them, and think that you are in paradise.”
—Henry David Thoreau (18171862)
“Friendship among nations, as among individuals, calls for constructive efforts to muster the forces of humanity in order that an atmosphere of close understanding and cooperation may be cultivated.”
—Franklin D. Roosevelt (18821945)