Is there a new Earth out there? | Katja Poppenhaeger | TEDxKlagenfurt

[Music]

[Applause]

I want to talk to you about something I

find really exciting and that is other

planets in our galaxy we have to

discover thousands of other planets out

there and other solar systems and most

of them are really different from our

home planet a lot of them are extremely

hot

and others are extremely cold and only a

few of them really a small fraction is

located at just the right distance to

their own Sun so that they have a

moderate temperature this is what we

call the habitable zone around a star

and it’s where water can be present in

liquid form on the planetary surface

this is the basic prerequisite for life

as we know it

so I want to take you on a journey to

three star systems and we’ll take a look

at what planets and the habitable zones

might look like we’ll start a journey

here on earth and as you all know it is

a habitable planet and as you also know

we haven’t been treating our own planet

particularly well lately it’s almost as

if we’re try trying to turn it into an

inhabitable planet so let’s just say we

actually managed to do that right we

messed it all up

we made it inhabitable we can’t stay

here we actually have to go out and find

ourselves a new home so what do we do

let’s say we have a spaceship it’s

really fast it can travel at the fastest

speed possible which is the speed of

light so we get in we all get in we

switch on the engine we start and whew

we fly past the moon after just one

second and after eight minutes we fly by

the Sun and then we leave the solar

system our first destination is the star

Proxima Centauri

it’s our closest neighbor in space the

nearest star to us and even though it’s

our closest neighbor and we’re traveling

at the fastest speed possible it will

take us roughly four years to get there

because space is pretty damn big so when

we arrived there we found out hey we’re

really lucky there actually is a planet

in the habitable zone and when we land

there

it might look something like this we see

that there’s a dim red Sun in the sky

and we land on the surface and when we

look around and we actually happen to

see something like a tree we might

notice that all the leaves are black

because the plants have to gather all

the light that impinges upon them they

can’t just be green they have to be

black to absorb all the light they get

now we’ll notice something else that’s

very different from our home we will

notice that this planet is what we asked

a physicists called tidally locked that

means it always faces the same side to

its Sun and that means we have one half

of the planet that has eternal day and

we have another half that is eternal

night and where we might want to a set

up camp and try to stay there for a

while is that RIM around it where we

have eternal sunrise or eternal sunset

if you like that better so this is a

pretty exotic and fascinating view that

we have however we might notice that

there is something that makes our life

there really tough and the reason for

that is that Suns like our own Sun are

also Proxima Centauri they have not

these nice steady light sources that

they look like when we view them with

the naked eye actually when we look at

our own Sun up close like this you see

they have these spots on the surface

these bright spots and what you also see

for our Sun is it’s flickering it’s

moving we see really hot plasma doing

its intricate dance among the magnetic

fields on the solar surface and

sometimes we see bright flashes

happening these we call flares and they

emit lots of high-energy photons x-rays

lots of charged particles and this is

only what our good old quiet Sundance

for something like Proxima Centauri we

know that these flares are much more

violent there will be huge magnetic

loops there will be huge eruptions of

the stellar surface and this is really

bad news for us on our little planet

there because these violent flares and

the particles coming out from the star

might strip away the atmosphere of the

little planet well that’s bad for us

right we’d like something to breathe so

what we have to do is actually you have

get back into a spaceship and we have to

keep traveling and find ourselves a

better place to live now let’s go for

something else that’s exotic but also

really fascinating let’s go for an EXO

moon an X alone is a moon that circles

around a planet in another solar system

let’s go for a moon that circles around

massive planets something like our own

Jupiter or Saturn when we land on that

tiny moon we don’t have just the Sun in

the sky we also have a big planet in the

sky is a fantastic view if you imagine

that right now what we also might notice

with our giant planet hanging there if

that we have northern lights on such a

planet and now this is not an artist’s

impression this is real photographic

data from our own solar system this is

our Saturn and there are actual northern

lights on it that were imaged with

another telescope there fantastic

imagine having that in your sky all the

time it’s great isn’t it

and now this is good news because not

only are the Northern Lights beautiful

they also mean that the giant planet has

a magnetic field and such a magnetic

field can shield us can be a guard

against the negative effects that flares

from the Sun can have on us so if we’re

here with our tiny X a moon somewhere

here we are shielded by that magnetic

field and our atmosphere will not be

stripped away as in the case of Proxima

Centauri so that’s great but something

else that we might notice is if our moon

is not in a perfectly circular orbit

what will happen is that the

gravitational force from that massive

planet there will squeeze and squish the

interior of our Moon and if you squeeze

and squish the interior of the moon or

of the planet you get something and that

is volcanoes no volcanoes are pretty

awesome it’s it’s a really cool thing to

look at right but it won’t be just any

old volcano like we have on earth it’s

going to be massively large volcanoes so

what I’m gonna show you again is a real

picture from our own solar system from

one of Jupiter’s moons and you will see

a massive volcanic eruption here on the

rim this is this is really intense

because what you see there is 150

kilometers high

imagine that 150 kilometers now you

don’t want to live next to a volcano

that produces a 150 kilometer large ash

cloud you don’t want that right so you

might say hey you know what you can live

somewhere here that’s that’s all right

right no it’s not tough luck because

that’s another volcanic eruption going

on here so being on such an EXO moon is

maybe not such a great idea for us to

live there to stay there to build a life

there so with a heavy heart even though

we have this beautiful outlook on the

giant planet we get back into our

spaceship and this time we might

actually aim for something that is a bit

more familiar the exotic places are

great but this time that’s aim for

something that’s really similar to a

solar system we are looking for

something that we as astrophysicists

call a solar twin this is a star that

has pretty much the same mass and

temperature as our own Sun and have a

few of those around actually to get to

the closest one to us we have to travel

for around about 40 years in our super

fast spaceship but well we’ll make it

we’ll get there after 40 years and let’s

say we really have a lot of luck and

there is actually something like an

earth-sized planet and somewhat

earth-like orbit and what we’re really

hoping for is of course something like

this when we get closer right you want

to see something that actually has

oceans that has water but if that planet

that we see there isn’t an orbit that’s

only three percent smaller than our

Earth’s orbit what we might rather see

is something like this a planet that’s

completely shrouded in acid clouds and

below those clouds of acid there’s an

air and surface more than 400 degrees

hot so how do we know this well this is

actually Venus from our own solar system

it doesn’t take much to turn something

that might have become an earth into

something like Venus it’s just a few

percent change in orbit and now there we

are right we traveled all this distance

we looked at all these fantastic places

and still we haven’t found a place to

live so what does this mean for us there

are a lot of planets out there in our

galaxy actually we know that on average

there’s one planet per star out there so

that’s really really a lot of planets

right and there will be a few of those

that will be like earth but none of them

is just around the corner there’s no

second home for us near to us so here’s

what I want us to do here’s what I want

all of us to do I want us to keep

reaching for the stars but to take good

care of our planet at the same time

let’s not mess it up thank you [Applause]