- [Narrator] Astronomers have found dozens of potentially
habitable planets outside of our solar system.
That's dozens of chances to discover the first alien life.
Or, you know,
plenty of places we could park our first
interstellar colonies.
But with so many options, how do we know which is best?
You might think that most Earth-like planets
should be at the top of our list.
After all, we've got everything we need.
Water, land, an atmosphere,
and trillions of life forms lapping it all up.
But according to a small group of researchers,
there are bigger and better planets out there.
They're called super-Earths.
Super-Earths may be some of the most common
planets in our galaxy.
Since 2009,
Kepler Space Telescope has discovered about 4000 exoplanets.
30% of them are super-Earths,
and a few percent of those super-Earths
orbit within their host star's habitable zone.
That's the Goldilocks Zone,
where the planet's surface is just the right temperature for
liquid water.
Not too cold, not too hot.
Now, there's a chance some of these super-Earths
aren't rocky worlds like Earth.
The larger ones could be made out of mostly
hydrogen and helium gas,
like Jupiter and Saturn,
which would not be very hospitable for life.
But the reality is,
astronomers are still gathering details
as more data comes in.
So, in the meantime,
let's explore what life on a rocky, habitable super-Earth
might be like.
Liquid water is just the start.
These planets can be almost double Earth's radius,
and up to 10 times more massive.
And all that extra mass is what researchers think
could really make super- Earths the perfect home.
That's because more massive planets have
a stronger gravitational pull.
super-Earth Kepler 20b, for example
is nearly double the size of Earth,
and it's 10 times more massive.
This makes its surface gravity almost 3 times stronger.
That stronger gravity means that the planet can hold
on to more air molecules and form a thicker atmosphere,
which is great for protecting against
harmful space radiation.
It also means mountains and hills would erode a lot faster,
leaving a relatively flatter surface, compared to Earth.
Now that might sound boring,
but scientists think this could actually spawn dozens
of shallow islands all across the planet.
Those in turn,
could be the perfect place for life to form and evolve.
Just as biodiversity in Earth's oceans is richest
in shallow waters near coastlines,
such an "archipelago world"
might be enormously advantageous to life.
There's just one problem,
leaving this tropical paradise would be extremely difficult.
The escape velocity on Kepler 20b
is more than double compared to Earth's,
which means either rockets would need more fuel
to reach their destinations...
Like for example,
a mission similar to the Apollo Moon Landing
would require twice the amount of fuel.
Or, rockets would have to carry only a fraction
of the payload.
For instance, SpaceX's Falcon Heavy can launch 50 thousand
kilograms of payload into Earth's orbit.
Whereas it could only launch 40 kilograms
into orbit around a super- Earth like Kepler 20b.
That's about the weight of a German Shepherd.
Suffice it to say,
leaving a super-Earth would be a far greater challenge.
But if it looked like this,
would you really want to say goodbye?
We'll never know for sure until we visit one.
What questions do you have about space?
Leave your queries and the comments below.
And thanks for watching.