Is it possible we should be looking for life-supporting planets a little differently?
Maybe.
And maybe that’s a good thing.
Hey guys, Amy here for DNews, and one of the most compelling things we’re doing in space
is looking for other Earth-like planets that could harbour life orbiting other stars.
When we look for life on exoplanets, we typically look for Earth-like planets in Earth-like
places, that is, terrestrial planets that orbit their star’s habitable zone, that
magic zone where water can exist as a liquid on the surface.
But new research from Cornell University says we might want to broaden our search.
For young solar systems, the habitable zone around a host star can actually be much further
from that star than previously thought.
That’s because young stars are hotter; stars gradually cool as they age.
And this is good news in the search for exoplanets because it’s easier to detect planets slightly
farther away from their stars.
And because stars can cool for up to 2.5 billion years, it's possible that life could begin
on a planet during its star’s early life when the star’s habitable zone is further
away because it’s much hotter.
As the star cools and the habitable zone shrinks, that life could theoretically move to the
planet’s subsurface or underground oceans.
So there could be life on planets well outside a star’s current habitable zone.
But there are other factors at play here, like if a runaway greenhouse effect is triggered.
This happens when a planet absorbs more energy from its star than it can radiate back to
space, which can lead to a rapid evaporation of surface water.
But that doesn’t mean the planet will be forever lifeless.
A planet could still become habitable if water somehow arrives after the runaway phase ends,
like a late heavy bombardment of water-rich asteroids.
That’s what happened to the Earth.
Some of our water arrived after this early runaway phase from a heavy bombardment of
water-rich asteroids.
So when it comes to looking for life on other planets, looking at nascent systems around
young stars might be a better way to look.
It doesn’t change things immediately, but are you guys excited at what widening our
search for life on other worlds might reveal?
Let us know in the comments below or you can catch me on Twitter as @astVintageSpace.
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