If conditions had been just a little different an eon ago, there might be plentiful life on Venus and none on Earth, according to a hypothesis by Rice University scientists.
The researchers maintain that minor evolutionary changes could have altered the fates of both Earth and Venus in ways that scientists may soon be able to model through observation of other solar systems, particularly ones in the process of forming, according to Rice Earth scientist Adrian Lenardic.
Lenardic and his team suggested that habitable planets may lie outside the “Goldilocks zone” in extra-solar systems, and that planets farther from or closer to their suns than Earth may harbor the conditions necessary for life.
The Goldilocks zone has long been defined as the band of space around a star that is not too warm, not too cold, rocky and with the right conditions for maintaining surface water and a breathable atmosphere. But that description, which to date scientists have only been able to calibrate using observations from our own solar system, may be too limiting, Lenardic said.
“For a long time we’ve been living, effectively, in one experiment, our solar system,” he said, channeling his mentor, the late William Kaula. Kaula is considered the father of space geodetics, a system by which all the properties in a planetary system can be quantified.
In expanding the notion of habitable zones, the researchers determined that life on Earth itself isn’t necessarily a given based on the Goldilocks concept. A nudge this way or that in the conditions that existed early in the planet’s formation may have made it inhospitable.
By extension, a similarly small variation could have changed the fortunes of Venus, Earth’s closest neighbor, preventing it from becoming a burning desert with an atmosphere poisonous to terrestrials.
The paper said the idea that plate tectonics is a critical reason Earth harbors life is questionable. “The Earth in its earliest lifetimes, let’s say 2-3 billion years ago, would have looked for all intents and purposes like an alien planet,” Lenardic said. “We know the atmosphere was completely different, with no oxygen. There’s a debate that plate tectonics might not have been operative…The Earth itself could have transitioned between planetary states as it evolved.”
Even Venus, if it had the chance would have evolved a new life on its surface, they suggested.