Oxygen accounts for about 21% of Earth's air, with the rest of our atmosphere primarily nitrogen.
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Earth's planetary neighbor Venus offers quite a different story. Its thick and noxious atmosphere is dominated by carbon dioxide 96.5 with lesser amounts of nitrogen and trace gases. Oxygen is nearly absent.
Using an instrument aboard the SOFIA airborne observatory, a Boeing 747SP aircraft modified to carry an infrared telescope in a joint project between NASA and the German Aerospace Center, scientists have now detected atomic oxygen in a thin layer sandwiched between two other layers of the Venusian atmosphere.
They noted that this atomic oxygen, which consists of a single oxygen atom, differs from molecular oxygen, which consists of two oxygen atoms and is breathable.
The researchers directly detected oxygen for the first time on the side of Venus facing the sun where it actually is produced in the atmosphere as well as detecting it on the side facing away from the sun, where it previously was spotted by a ground-based telescope in Hawaii. Venus rotates much more slowly than Earth.
The thick atmosphere on the second planet from the sun traps in heat in a runaway greenhouse effect.
The oxygen is produced on the planet's day side by ultraviolet radiation from the sun that breaks down atmospheric carbon dioxide and carbon monoxide into oxygen atoms and other chemicals, the researchers said.
Some of the oxygen is then transported by winds to the Venusian night side.
On Venus, there is a layer of clouds containing sulfuric acid up to a height of about 40 miles (65 km) above the planetary surface, with hurricane-force winds blowing in the opposite direction of the planet's rotation. About 75 miles (120 km) above the surface, strong winds blow in the same direction as the planet's rotation.
The oxygen was found to be concentrated between those two ferocious layers, at an altitude about 60 miles (100 km).
The oxygen's temperature was found to range from about minus 184 degrees Fahrenheit (minus 120 degrees Celsius) on the planet's day side to minus 256 degrees Fahrenheit (minus 160 degrees Celsius) on its night side. ■