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The atmosphere has a mass of about 5.15 × 10 18 kg, [2] three quarters of which is within about 11 km (6.8 mi; 36,000 ft) of the surface. The atmosphere becomes thinner with increasing altitude, with no definite boundary between the atmosphere and outer space.
Earth's biosphere has significantly altered its atmosphere. Oxygenic photosynthesis evolved 2.7 Gya, forming the primarily nitrogen–oxygen atmosphere of today. [62] This change enabled the proliferation of aerobic organisms and, indirectly, the formation of the ozone layer due to the subsequent conversion of atmospheric O 2 into O 3.
An atmosphere (from Ancient Greek ἀτμός (atmós) 'vapour, steam' and σφαῖρα (sphaîra) 'sphere') [1] is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low.
On Earth, the atmosphere warms the planet, contains the oxygen people breathe, protects against solar radiation and creates the pressure needed for liquid water to remain on the planet's surface.
The earth’s atmosphere has several layers, what NASA calls “a multi-layered cake. We live in the troposphere, which in the U.S. extends about 6 miles above the earth’s surface. It’s where ...
The discovery that GJ 1132b has an atmosphere is a key step in the search for life outside our solar system. Scientists confirm 'Earth-like' planet with atmosphere discovered 39 light-years from Earth
The estimated mean volume ratio of molecular oxygen (O 2) in the Martian atmosphere is 0.174%. [3] It is one of the products of the photolysis of CO 2, water vapor, and ozone (O 3). It can react with atomic oxygen (O) to re-form ozone (O 3). In 2010, the Herschel Space Observatory detected molecular oxygen in the Martian atmosphere. [90]
Mercury, being the closest to the Sun, with a weak magnetic field and the smallest mass of the recognized terrestrial planets, has a very tenuous and highly variable atmosphere (surface-bound exosphere) containing hydrogen, helium, oxygen, sodium, calcium, potassium and water vapor, with a combined pressure level of about 10 −14 bar (1 nPa). [2]