As of right now, Earth is the only place in
the entire universe where life is known to exist. We've been searching far and
wide. Mars, Venus, Titan, Europa, and yet so far we've found nothing. But
when you stop to consider that there are more stars in the universe than grains of
sand here on Earth and nearly every Star has its own planets it's hard to imagine
that Earth is the only inhabited world. And we've found some pretty promising options.
So let's go for a little journey to the most exciting exoplanets ever discovered. But these
planets aren't boring and dry like Mars these are super habitable worlds that are bigger,
better and more suited for life than Earth... This planet is considered to be the best
candidate for a superhabitable world. A massive rocky world twice the size of Earth
orbiting in the habitable zone of its star. This means that the conditions are just right
for liquid water to exist on the surface, a key ingredient for life as we know it. Imagine
a world so big that you could spend over 100 hours flying between continents. There would be so much
more land for life to thrive on compared to here on Earth. It orbits a very special kind of star.
You see our sun is a G-type main sequence star sometimes referred to as a yellow dwarf and
these stars only hang around for 10 billion years. Our sun is nearly halfway through its
entire life cycle meaning in around 5 billion years the sun will expand into a red giant
star could consuming the Earth in the process. But in the case of KOI 5715.01, dreadful name I
know, it orbits an orange dwarf star these stars are a little smaller than our sun but they are
so much more stable. In some cases hanging around for up to 70 billion years. Life on Earth has been
evolving for just 4 billion years. Can you imagine what life might look like after 70 billion years
of evolution? That's when you start getting into tier 3 civilizations and Dyson Sphere territory.
While this world does sound perfect and I'm sure you want to move there right now I have to be
honest with you, this planet is so far away. I'm talking 3,000 light years away, meaning that
if you and I wanted to leave today and head on a trip to visit this planet and we somehow convinced
NASA to lend us an Orion spacecraft it would still take us over 100,000 years. Maybe one day we'll
have a rocket quick enough to get us there in a reasonable amount of time but for now we can
only dream about what interesting life forms might be thriving over there. Maybe we should
check out something a little closer to home... Just 39 light years away, we come
across a potential safe haven for life. Seven Earth-sized worlds huddled tightly around
their star, three of which orbit within the habitable zone. This is the Trappist-1 system,
first discovered back in 2017 and for the last five years astronomers have been spending every
waking minute researching the system in an attempt to find life. So they were able to detect this
gold mine of planets by looking at how the star's brightness dipped ever so slightly as each planet
passed between us and the star. This is known as the transit method. These planets are much
older than Earth, meaning life there would have had at least 3 billion years to evolve before
Earth was even finished forming. Trappist-1e, the fourth planet from the star is of particular
interest to us. It's a little smaller than Earth and it has the right conditions for water to
exist on the planet and we think it may have a thick oxygen atmosphere even better for life than
the atmosphere here on Earth. But let's be clear, this system is very different to ours. The planets
are orbiting a tiny red dwarf star of a similar size to Jupiter the star is far cooler than
our sun meaning these planets have to be close, so close that the orbits of the entire system
would easily fit within Mercury's orbit of the Sun. This can cause some problems. We think
that the planets are tidally locked to their star. One side being permanently cooked by the
star and one side being frozen and desolate. Under perfect conditions, this could create a
single strip of land around the planet where the conditions are just right for life. But
what's most exciting to me is imagining what living on these planets would actually
be like. They are so close together that you would look to the sky and see these
massive planets orbiting alongside you. You could take holidays to different planets as if
they were countries. Visit the slopes for a skiing trip out on Trappist-1H before going for a summer
holiday to the tropical world of Trappist-1d and since it's just 39 light years away maybe one
day this could be a reality for humanity... Up next we have Kepler-452b, a world that has
often been called Earth 2.0. The planet shares so many similarities with Earth that it's kind of
scary. It orbits a sun-like star every 384 days, that's just five percent longer than our year here
on Earth. This would also make every single month exactly 32 days which just kind of feels right...
This is a super Earth though, meaning it's roughly 50 percent bigger than Earth. This means more
land, larger continents and potentially more water... It's looking good so far but it does come
with a few downsides. While it is just 50% larger than Earth, it's actually five times more massive
meaning gravity will feel twice as strong on the surface and everyone therefore will weigh twice as
much. But here's where things get interesting... As far as we can tell, this is the only planet
in the Kepler-452 system. That means no gas giant planet and I know what you're thinking,
Jupiter protects us from asteroids here on Earth so wouldn't this planet just be completely
destroyed by asteroids? But that's where you're actually wrong, you see we thought for decades
that Jupiter was our friend, regularly protecting us from asteroid impacts. But recent simulations
have come out to show that this might not actually be true. The paper showed that a solar system
without Jupiter would actually have 3.5 times less asteroid collisions here on Earth. So since
kepler-452b is all alone maybe a civilization on the planet wouldn't have to worry about asteroid
collisions at all. But it is far from perfect, its star is slightly older than our own and as
sun-like stars become older they tend to become more energetic and as a result the planet might
be receiving too much radiation slowly warming the planet and eventually leading to a runaway
greenhouse effect. This could leave the planet looking a lot less like Earth and more like Venus
killing off all life on the planet for good... We end our journey 600 light years away from home
in the distant constellation of Cygnus. This is Kepler-22b one of the most interesting super
Earths ever discovered. This planet has stumped astronomers for years, it orbits well within the
habitable zone and our best observations point towards this planet being a true water world,
just like Miller's planet from Interstellar. A massive ocean covering the rocky inner core that
is hundreds of kilometers deep. It is possible that life may have evolved in the depths of this
ocean. Strange fish that only seem real in your wildest dreams. If humans ever did make the
journey across the Galaxy to visit Kepler-22b, I'm sure we would be in for a surprise. So
the real question is, which planet do you think you would want to move to? For now
I think I'll be staying here on Earth...
