Earth is an oceanic world, with approximately 71% of its surface covered by water. Our nearest neighbor, Venus, is sometimes called Earth’s twin based on their similar size and rocky composition. While its surface is parched and barren today, might Venus have once been covered with oceans?
The answer is no, according to new research that estimated the amount of water in the planet’s interior – a key indicator of whether Venus ever had oceans – based on the chemical composition of its atmosphere. The researchers concluded that the planet’s interior is largely dry at present, which is consistent with the idea that Venus was left dry after an early era in its history when its surface was composed of molten rock – magma – and After that a dry surface was formed.
Water is considered an essential ingredient for life, so the study’s findings suggest that Venus was never habitable. The findings provide no support for the previous hypothesis that Venus may have reserves of water beneath its surface, a remnant of a lost ocean.
Volcanoes provide clues about the interiors of rocky planets by venting gases into a planet’s atmosphere. As magma rises to the surface from an intermediate planetary layer called the mantle, it expels gases from deeper parts of the interior.
Volcanic gases on Earth are more than 60% water vapor, evidence of a water-rich interior. The researchers calculated that the gases in Venus’s eruptions contained no more than 6% water vapor, indicating a dry interior.
“We suggest that the habitable past would be associated with Venus’s present-day interior being water-rich, and the arid past would be associated with Venus’s present-day interior being dry,” said Dr. Tereza Constantino said. The authors of the study published Monday in the journal Nature Astronomy.
“Atmospheric chemistry shows that volcanic eruptions on Venus produce very little water, meaning that the planet’s interior – the source of volcanism – is uniformly dry. This is consistent with what Venus’ surface It remained dry for a long time and was never habitable,” Constantino added.
Venus is the second planet from the Sun and Earth is the third.
“Two very different histories of water on Venus have been proposed: one where Venus had a temperate climate for billions of years with liquid water on the surface, and another where early warm Venus was never able to condense surface liquid water. ,” Constantino said. ,
Venus’s diameter of about 7,500 miles (12,000 km) is slightly smaller than Earth’s 7,900 miles (12,750 km).
“Venus and Earth are often called sister planets because of their similarity in mass, radius, density and distance from the Sun. However, their evolutionary paths diverged dramatically,” Constantino said.
“Venus’ surface conditions are now extreme compared to Earth, with atmospheric pressure 90 times higher, surface temperatures rising to about 465 °C (869 °F), and a toxic atmosphere with sulfuric acid clouds. These apparent contradictions underscore the unique challenges of understanding Venus as far more than its Earth counterpart, Constantino said.
It appears the story is different on Mars, the fourth planet from the Sun.
Features of Mars’ surface indicate that there was an ocean of liquid water billions of years ago. No such feature has been found on Venus. According to research published in August based on seismic data obtained by NASA’s robotic InSight lander, Mars may contain a large reservoir of liquid water within fractured igneous rocks beneath the surface, enough to fill an ocean. Will cover its entire surface.
While Venus is less studied than Mars, new exploration is planned. NASA’s planned DAVINCI mission will investigate Venus from its clouds to its surface during the 2030s using both a flyby and a descent probe. Also during the 2030s, the European Space Agency’s Envision orbital mission is scheduled to conduct radar mapping and atmospheric studies.
“Venus provides a natural laboratory to study how habitability – or the lack of it – evolves,” Constantino said.
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