[LINK] "Was Venus the first habitable planet in our solar system?"

[rfmcdonald]

The Guardian's Hannah Devlin reports on new models of Venus' environment which suggest this world was very broadly Earth-like well into the history of solar system. This is tantalizing, not least because of the prospects for life.

Its surface is hot enough to melt lead and its skies are darkened by toxic clouds of sulphuric acid. Venus is often referred to as Earth’s evil twin, but conditions on the planet were not always so hellish, according to research that suggests it may have been the first place in the solar system to have become habitable.

The study, due to be presented this week at the at the American Astronomical Society Meeting in Pasadena, concludes that at a time when primitive bacteria were emerging on Earth, Venus may have had a balmy climate and vast oceans up to 2,000 metres (6,562 feet) deep.

Michael Way, who led the work at the Nasa Goddard Institute for Space Studies in New York City, said: “If you lived three billion years ago at a low latitude and low elevation the surface temperatures would not have been that different from that of a place in the tropics on Earth,” he said.

The Venusian skies would have been cloudy with almost continual rain lashing down in some regions, however. “So while you might get nice sunsets you would have mostly overcast skies during the day and precipitation,” Way added.

[. . .]

Way and colleagues simulated the Venusian climate at various time points between 2.9bn and 715m years ago, employing similar models to those used to predict future climate change on Earth. The scientists fed some basic assumptions into the model, including the presence of water, the intensity of the sunlight and how fast Venus was rotating. In this virtual version, 2.9bn years ago Venus had an average surface temperature of 11C (52F) and this only increased to an average of 15C (59F) by 715m years ago, as the sun became more powerful.