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  • It's a bird, it's a plane, it's a super... earth.

  • Perhaps one of the most revolutionary discoveries in modern astronomy is the discovery of an

  • entirely unpredicted class of planets known as 'super earths'.

  • These rocky planets mass from anywhere between 2 to 10 times Earth's own mass, are believed

  • to have a rocky core, and some might even be better suited for life than our own planet.

  • It was initially believed that the most common type of planet in the solar system were gas

  • giants- it was a gas giant after all that was the first exoplanet ever discovered by

  • mankind.

  • However, as our ability to spot planets in other solar systems increased, scientists

  • made a shocking discovery- it wasn't gas giants or even small rocky planets like Mercury that

  • were the most common, but rather large, rocky planets, though as smaller planets are more

  • difficult to discover our findings may still be accidentally biased.

  • So why did scientists go with the term Super Earth?

  • The name comes from the fact that along with a rocky core, these planets are able to retain

  • a significant atmosphere- features found in only two planets in our own solar system,

  • Earth and Venus.

  • However, the name can be misleading, and many have fundamentally misunderstood the nature

  • of a super earth.

  • When you think of a super earth after all, you're probably thinking of a planet that's

  • largely like our own earth, rocky with oceans and a welcoming atmosphere- but that's not

  • what super earths are at all.

  • Or at least, that's not what most super earths are like.

  • 55 Cancri e for example, is a super earth completely covered by an ocean of lava hot

  • enough to melt iron, basically making it the Mount Doom of planets.

  • Meanwhile, Gliese 1214 b is believed to be the polar opposite, a water world completely

  • covered by an ocean.

  • Within these two extremes, scientists have found a plethora of worlds.

  • Initially scientists believed that super earths could be super-habitable, and have even better

  • conditions for life than our own planet.

  • Their increased size would offer more surface area for life, and be less perturbed by the

  • gravity of nearby objects and thus offer more climate stability to its inhabitants.

  • On our own planet the leading cause of extinction is climate change, with periodic ice ages

  • wiping out vast numbers of species.

  • At the time, it seemed like the name super earth was quite apt, as these worlds would

  • be far more habitable than earth.

  • However, as scientists refined their knowledge of the physics and geological processes on

  • these super earths through experimentation, a different story began to emerge.

  • Firstly, the sheer mass of these planets means that many of them are bound to be water worlds.

  • The increased gravity would attract greater amounts of icy comets than our own smaller

  • earth did, leading to planet-spanning oceans that could be miles deep.

  • And what's wrong with that, you might ask, after all life almost certainly began in the

  • ocean on our own planet, and the ocean remains far more biodiverse than land does.

  • More water should mean more life, right?

  • Well, the biggest problem with a large water world is that the increased gravity and great

  • depth of its oceans would smash water molecules together into ice formed not by low temperatures

  • but incredible pressure.

  • This extremely dense layer of ice would act as a form of sealant around the rocky core

  • of the planet, blocking off the core from the surface and shutting off the carbon cycle

  • for the world.

  • This may be biased towards carbon-based life forms, but even if non-carbon based lifeforms

  • are possible, this thick ice layer would shut off vital minerals regularly exposed by geological

  • processes on smaller worlds, and prevent them from entering the biological life cycle.

  • Even if you aren't covered in water, that big gravity field is going to be a problem

  • for the exact same reason- a super earth is going to attract a lot more celestial objects,

  • and thus be prone to much more extinction level events from asteroid impacts.

  • While that wouldn't preclude life entirely, cyclical extinction level impacts certainly

  • would make the evolution of intelligent life extremely difficult, if not impossible.

  • Super earths could also be prone to attracting more gas and thus have much thicker atmospheres

  • than here on our regular old dumb earth.

  • A much more dense atmosphere comes with a whole host of problems, and we need only look

  • at Venus for one very good reason why a super earth with a thick atmosphere would be uninhabitable.

  • Temperatures on the surface there are hot enough to melt lead, and while the planet

  • is closer to the sun than we are, it is still well within the habitable range of our sun.

  • Venus' thick, oppressive atmosphere is the real reason for its uninhabitable surface

  • temperatures, and a super earth with a similarly thick atmosphere would likely suffer from

  • the same life-killing global warming effect.

  • Another nail in the coffin for super earth habitability is the effect of the planet's

  • mass on its core.

  • Our own core is only partially molten, and its rotation maintains a powerful electromagnetic

  • field which protects life on earth from cosmic radiation.

  • On a super earth though, the massive pressures at the core from the increased mass of the

  • planet makes it extremely unlikely that its core would remain liquid for very long- perhaps

  • only a couple of billion years before it inevitably solidifies into a solid core.

  • While life could certainly evolve during the time the core was liquid, it would very quickly

  • find it difficult to survive as the planet's magnetic field weakened and eventually collapsed

  • entirely.

  • DNA is very delicate, and while some radiation is good to promote mutations that can spur

  • on evolution, too much radiation leads to the breakdown of DNA.

  • Life on a super earth with a solid core would likely only be very simple, and only exist

  • in places shielded by cosmic radiation.

  • However, it's not all doom and gloom and super earths could possibly give rise to a void

  • ecology- or life that exists in outer space.

  • We know that there are organisms from our own planet that can exist for a short time

  • in space, so the idea of a void ecology is not completely out of the question.

  • However, the problem with looking for space-faring lifeforms is that as far as we know it, life

  • cannot get started in the extremely harsh environment of space.

  • It must start somewhere more hospitable, and then make the move to space.

  • Super earths with solidifying cores could be the perfect nursery for a void ecology,

  • with organisms becoming increasingly resistant to cosmic radiation via the slow, multi-million

  • year process of the planet losing its magnetic field.

  • All it would take then is a lucky asteroid impact to knock debris infected with these

  • lifeforms into outer space, an improbable, but not impossible proposition.

  • However, for life as we know it, super earths are looking increasingly unlikely to be hospitable.

  • But, scientists have high hopes for a class of super earths that range in the low end

  • of the scale, with mass only twice as big as our own earth.

  • These smaller super earths have many of the advantages of larger super earths- climate

  • stability, longer molten core life span, larger surface areas- without the disadvantages of

  • being as big as their larger cousins.

  • These super habitable worlds may end up being havens for life, even intelligent life- though

  • the increased gravity would make rocketry more difficult and expensive, perhaps greatly

  • delaying or even preventing a species from ever making it into space.

  • Earth may turn out to be a backwater planet that's barely habitable by alien standards,

  • but seeing as it's the best we've got in our galactic neighborhood, we'd better start taking

  • problems like global warming and pollution seriously, because there's nowhere to run

  • to.

  • Now go watch Space Chief Makes Shocking Alien Confession, or click this other video instead!

It's a bird, it's a plane, it's a super... earth.

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Scientists Discover "Super Earth"

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    林宜悉 posted on 2021/03/24
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