Scientists: Earth Barely Supports Life
It’s all about plate motion and resulting carbon dioxide recycling.
Thinner plates are weaker and more easily moved and so able to support the kinds of crucial planet-shaping plate tectonics experienced on this planet over the billions of years that life evolved from simple one-celled organisms to complex creatures that can fly, swim and read.
… as plates spread apart from each other, slide under one another, and even crash into each other to lift gigantic mountain ranges like the Himalayas, they also recycle carbon dioxide. This greenhouse gas acts as a thermostat to keep Earth balmy ” but not scorching ” over geologic time scales.
Water plays a large role, too. Last night, D and I watched Alien Planets and Alien Moons, two episodes in The History Channel’s new The Universe series. The shows explained the various extrasolar planets discovered, their characteristics and human motivation to look for such places, but didn’t delve deep into their common size, tectonic, climactic (moisture) requirements. This article provides more insight.
[Scientists] examined so-called super-Earths more than twice the size of Earth and up to 10 times as massive. Any heftier and the planet would have enough tug to collect gas, transforming it into a Neptune- or Jupiter-like world, theory holds … simulations showed that rocky orbs with masses three times that of Earth and greater should experience plate tectonics. Earth was found to be a borderline case, which is supported by the fact that the slightly smaller planet Venus is tectonically inactive. The reason for plate tectonics on Earth, Valencia said, is water, which would increase the pressure within the ground beneath us and so weaken the plates enough to nudge plate tectonics. Venus has no water.
[Water is important for plate subduction and fault activation, but what about mid-ocean ridges where plates come apart?]
The requirements so far: A rocky planet up to 10 times the size of earth, carbon dioxide release and recycling, water … a certain age, a certain distance from its sun. The search continues.
Related: Space.com: Top 10 List of Habitable Stars to Guide Search
3 – 10 time the size of the earth?
Whats with that?
Heh. We were watching one of those Universe shows in our hotel room in Chicago last week. The problem with ’em is the same commercials at the breaks, over and over and over again. I finally had to ask the little guy to quit asking me about why the goldfish was gasping in the shallow water in the asthma commercial.
I meant “up to 10 times the size of earth” for a requirement.
They looked at planets 2-3x and up to 10x the size of earth to see how big a planet can get before it cannot sustain earth-like conditions.
I was wondering if you were planning on moving.
Why is that a requirement, surely a planet the same size as this one and possible a little smaller would work also.
I’m a huge Europa fan. All the Galilean moons really. But Europa, she’s a fine one.