Scientists have, for the first time, directly detected significant signs of atomic oxygen in the daytime atmosphere of Venus, suspended above the toxic cloud layer, possibly with a cooling effect.
Venus is a world that scientists eagerly want to study in detail. It shares similarities in mass and composition with Earth, but while Earth is lush, humid, and teeming with life, Venus is a lifeless death valley. Covered by thick, suffocating clouds of carbon dioxide, the surface temperature averages around 464°C.
These clouds also rain acid on Venus, and the entire atmosphere rotates around the planet at an astonishing speed, with winds below the cloud layer reaching speeds of about 700 kilometers per hour. On Earth, the highest recorded wind speed is 407 kilometers per hour.
We don’t know why Venus and Earth are so different, and studying Venus can help us understand whether Venus and Earth once followed the same path until a certain point where they diverged.
According to theoretical models, atomic oxygen (different from the molecular oxygen we breathe) is known to exist in the Venusian atmosphere.
Atomic oxygen consists of a single oxygen atom, has a short lifespan, and is highly reactive, easily combining with other atoms. On Earth, molecular oxygen in high-altitude regions undergoes photodissociation, producing atomic oxygen. Scientists believe that a similar process occurs in the Venusian atmosphere primarily composed of carbon dioxide. When sunlight hits carbon dioxide, photodissociation breaks it down into atomic oxygen and carbon monoxide.
It’s well-known that Venus rotates very slowly, with a day on Venus equivalent to 243 Earth days. Therefore, atomic oxygen is a crucial substance in the intermediate and thermal layers of Venus.
Previous observations found atomic oxygen on the nighttime side of Venus, but it had not been observed on the daytime side. Researchers from various German institutions focused on data collected at 17 locations by the Stratospheric Observatory for Infrared Astronomy (SOFIA): 7 on the daytime side, 9 on the nighttime side, and 1 at the day-night boundary.
The research team was fortunate to detect atomic oxygen at all 17 locations, with the highest concentration at an altitude of 100 kilometers. This marks the first observation of atomic oxygen on the daytime side of Venus.
The team suggests that atomic oxygen on the daytime side is produced by the solar energy decomposition of carbon monoxide and carbon dioxide molecules. As the strong winds in the Venusian atmosphere carry atomic oxygen to the nighttime side, it may combine with other elements and form molecular oxygen.
Furthermore, atomic oxygen in the Venusian atmosphere may contribute to cooling the planet. When a single oxygen atom collides with other molecules such as carbon dioxide, energy transfers to the molecules and dissipates through radiation, leading to a cooler upper atmosphere on Venus.
The new findings are published in the journal “Nature Communications.“
