London, Oct 17 (IANS): While previous studies have suggested that Venus may have its own liquid water oceans, a new study suggested that this is not the case.
A team of astrophysicists led by the University of Geneva (UNIGE) and the National Centre of Competence in Research (NCCR) PlanetS, Switzerland, investigated whether our planet's twin did indeed have milder periods.
Using sophisticated three-dimensional models of the atmosphere, similar to those scientists use to simulate the Earth's current climate and future evolution, the team studied how the atmospheres of the two planets would evolve over time and whether oceans could form in the process.
"Thanks to our simulations, we were able to show that the climatic conditions did not allow water vapour to condense in the atmosphere of Venus," said Martin Turbet, astrophysicists and researcher at the Department of Astronomy of the Faculty of Science at UNIGE.
This means that the temperatures never got low enough for the water in its atmosphere to form raindrops that could fall on its surface.
Instead, water remained as a gas in the atmosphere and oceans never formed.
"One of the main reasons for this is the clouds that form preferentially on the night side of the planet. These clouds cause a very powerful greenhouse effect that prevented Venus from cooling as quickly as previously thought," Turbet said.
The results are published in the journal Nature.
Further, the astrophysicists' simulations also revealed that the Earth could easily have suffered the same fate as Venus.
If the Earth had been just a little closer to the Sun, or if the Sun had shone as brightly in its 'youth' as it does nowadays, our home planet would look very different today.
It is likely the relatively weak radiation of the young Sun that allowed the Earth to cool down enough to condense the water that forms our oceans.
It has always been considered as a major obstacle to the appearance of life on Earth. The argument was that if the Sun's radiation was much weaker than today, it would have turned the Earth into a ball of ice hostile to life.
"But it turns out that for the young, very hot Earth, this weak Sun may have in fact been an unhoped-for opportunity," the researchers said.