Venus is arguably the worst place in the solar system. A cloak of carbon dioxide suffocates the planet, subjecting its surface to skull-crushing pressure. Sulfuric acid rains down through the sickly yellow sky but never reaches the lava-licked ground. Venus is so hot — hot enough to melt lead — that the acid rain evaporates as it’s falling.
The planet’s extreme inhospitality is at the heart of one of the most beguiling mysteries in planetary science. Venus and Earth formed at the same time, from the same geologic building blocks, in pretty much the same part of the solar system. They’re even the same size. So why is Venus a hellscape, and Earth a garden?
A common refrain in the scientific community is that Venus is just several steps ahead — that it represents the end state of all large rocky planets, including Earth. The hypothesis is that these planets eventually lose the ability to sequester planet-warming greenhouse gases in their geologic underbelly. When those gases then accumulate in the atmosphere, the world enters a runaway greenhouse state — like the boiling hot Venusian climate. “Over the years, we’d always heard about Venus being a preview into Earth’s future,” said Stephen Kane, a planetary astrophysicist at the University of California, Riverside.
But is that long-held assumption true? In hundreds of millions or billions of years, will Earth’s climate go the way of Venus’, transitioning from a temperate world into a catastrophic hothouse? Kane and his colleagues have been trying to find out. Venus and Earth are often referred to as twins, with Venus being the evil one of the pair. In their Reuniting Twins project, the scientists have developed a digital model of Earth that combines solar physics, volcanology, plate tectonics and climate science. They’ve been pushing their model Earth to its extremes, trying every plausible way to break it and make it into Venus.
As well as exploring what went so wrong on the second rock from the sun, this work speaks to a query closer to home, said Paul Byrne, a planetary scientist at Washington University in St. Louis who was not directly involved with the project: “How long is Earth habitable for?”