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Are there other earths out there? | Amazing Space trivia for kids · The Curious Kidcast | Fun Facts and Curious Questions

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  What if I told you that right now, at this very moment, there
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  might be a kid on another planet sitting in their bedroom,
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  staring out of their window, wondering if there's anyone else
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  out there? What if that planet has oceans
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  and clouds and mountains and maybe even its own version of
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  pizza? And what if scientists are right
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  now, as you listen to this, trying to find it?
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  Today on the Curious Kid cast, we are going to find out whether
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  there is another Earth hiding somewhere in the universe.
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  And the answer is going to make your brain feel like it just did
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  a somersault. Stay with me.
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  Curious kid cast? Here we go.
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  Questions popping minds will blow.
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  Big ideas. They're taking flight.
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  Let's explore. Feel the light.
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  Welcome to The Curious Kid cast, the show where we take the
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  biggest, brainiest, most bonkers questions in the universe and
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  actually try to answer them properly.
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  I'm Charlie. And today, oh today we are going
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  on a journey so far from Earth that your brain might need a
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  seat belt. Right?
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  Before we dive in, I have to tell you what started today's
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  episode. A kid called Finn from
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  Edinburgh, Scotland was doing his homework one evening, not
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  paying attention to his homework obviously.
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  He was staring out the window at the night sky and he thought to
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  himself, if Earth is this good, surely someone else out there
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  made another one. His mum told him to focus on his
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  maths. Finn did not focus on his maths.
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  Instead he sent us a question. Are there other Earths out there
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  Finn? This one's for you, and your
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  maths homework is probably still waiting for you, buddy.
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  So are there other Earths out there?
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  Well, buckle up, because the answer is kind of mind melting,
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  kind of exciting and only a tiny bit terrifying.
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  Talk about what we even mean when we say another Earth.
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  Because if you just mean a big round thing flowing in space,
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  then yes, absolutely, we've found loads of those done
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  podcast over. But that's not what we mean when
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  scientists talk about another Earth.
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  They're looking for something very specific.
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  A planet that is roughly the same size as ours, at roughly
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  the right distance from its star.
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  So it's not a frozen ice lolly or a giant fireball, and in a
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  place where liquid water could actually exist on the surface.
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  Because here's the thing about water.
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  Life, as far as we know, absolutely loves water.
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  Every single living thing on Earth needs it.
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  So if a planet has liquid water, it's going to our maybe pile.
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  Now, a few decades ago, we had absolutely no idea if there were
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  any planets outside our solar system at all.
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  Zero. None.
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  We just had our eight planets plus poor Pluto who got demoted
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  and still hasn't got over it. And that was basically it.
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  Check back to episode 22, by the way, if you want to hear more
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  about what happened to Pluto. But then scientists got really
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  clever and started looking for planets around other stars.
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  These faraway worlds are called exoplanets.
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  Exo just means outside. So exoplanets are basically
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  outside planets. Very dramatic name for what is
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  essentially just a planet. Scientists love dramatic names.
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  And here's the bit that will genuinely blow your mind.
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  We have now found more than 6000 exoplanets. 6000, that's not a
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  typo. 6000 planets. That's more planets than there
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  are flavours of crisps, which I think we could all agree is a
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  lot. Now most of those planets are
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  absolutely terrible for life. Some are giant balls of gas
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  bigger than Jupiter. Some are so close to their star
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  that a year there lasts only a few days, which would make
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  birthday presents extremely expensive.
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  Some are so hot that it rains molten iron.
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  Iron falling from the sky like rain, but made of metal.
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  So don't forget your umbrella on that holiday.
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  But hidden in among all those bonkers worlds are some smaller,
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  rockier planets that have scientists very, very
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  interested. Some of them are in something
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  called the habitable zone. This is the region around a star
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  where the temperature is just right for liquid water to exist.
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  Scientists also call it the Goldilocks Zone, which I think
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  is the best scientific term ever invented because it means the
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  planet is not too hot, not too cold, but just right, just like
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  Goldilocks in the porridge, except hopefully without a large
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  angry bear turning up at the end.
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  We found some planets that seem to take quite a few of those
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  boxes. There's one called Kepler 452B,
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  which is often called Earth's cousin.
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  It orbits a star very similar to our sun, and it takes almost the
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  same amount of time to go round that star as Earth does to go
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  round ours. And Earth year is 365 days.
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  Kepler 452 B's year is 385 days. That's basically the same,
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  except you'd wait a little longer for Christmas, which I
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  think most kids would agree is actually worse.
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  Kepler 452B is also in its stars habitable zone, which means
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  temperatures there might allow liquid water.
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  But, and this is a big but, it's about 1 1/2 times the size of
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  Earth, which might mean it's more of a gassy mini planet than
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  a rocky surface one. We just don't know yet.
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  It's like being told there's a biscuit in a tin, but you can't
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  open the tin. You just have to stand there and
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  wonder about the biscuit. There's also something called
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  Trappist One, which is a star with seven planets orbiting
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  around it, some of which are Earth sized and in the habitable
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  zone. 7 planets in one system. That's like someone went
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  completely mad at the planet shop.
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  But before we get too excited, Trappist 1 is a small, cool Red
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  Star called a red dwarf, and red dwarfs have a bit of a habit of
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  throwing enormous flares of radiation at their planets.
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  That's basically the star having a tantrum and blasting
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  everything nearby with dangerous energy, which is not great if
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  you're to quietly develop life on the surface.
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  And there's a newer one too, discovered just this year
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  actually, called HD 137,000 and 10 B.
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  It's almost exactly the same size as Earth and takes a
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  similar amount of time to orbit its star.
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  Scientists were very excited. The Internet got very excited.
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  Headlines everywhere said things like, is this another Earth?
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  And then scientists look closer and went, ah, it might be
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  extremely cold, like very, very freezing cold.
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  So possibly not the tropical holiday destination we were
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  hoping looking for. Now here's something important
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  to know. When you see a headline that
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  says scientists discover Earth like planet, don't immediately
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  start packing your bags because earth like is a sneaky phrase.
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  It often just means the planet is similar in one or two ways.
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  Maybe it's the right size. Maybe it's the right distance
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  from its star. But we often know almost nothing
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  else about it. We don't know what it's air is
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  like. We don't know if it has oceans
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  or just rocks. We don't know if it's pink with
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  purple polka dots on the surface.
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  We just don't know. It's a bit like someone saying I
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  found and a house just like yours and it turns out they mean
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  it also has a front door. So how do scientists even find
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  these planets in the 1st place? Because you can't just look
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  through a telescope and see them.
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  They're way too tiny and the stars they orbit are way too
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  bright. It's like trying to spot a
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  single Ant standing next to a bonfire from the other side of
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  town. Scientists use two very clever
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  tricks. The 1st is called the transit
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  method. When a planet passes in front of
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  its star, it blocks a teeny tiny amount of the star's light.
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  We're talking about a dimming so small you'd never notice it with
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  your eyes. But space telescopes can spot
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  it, and if that dimming happens on a regular schedule, it means
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  something is orbiting the star and blocking the light each time
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  it passes. From that tiny flicker,
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  scientists can work out the size of the planet and how long it's
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  year is. It's basically the universe
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  version of a shadow puppet show. The second trick is called the
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  Wobble method, which is my personal favorite just because
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  of the name. Every planet has gravity, and
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  that gravity pulls on its star very slightly, making the star
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  wobble. Scientists can detect that tiny
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  wobble from billions of kilometres away and use it to
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  figure out that a planet is there.
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  The wobble method. Honestly, science is amazing.
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  But here's the problem. These methods work really well
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  for big planets or for planets that are very close to their
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  stars. Planets that are earth sized and
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  earth like distances are much harder to detect because their
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  signals are tinier. So ironically the most earth
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  like planets are the hardest ones to find.
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  It's like trying to find the quietest kid in a room full of
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  people doing kazoo solos. That's why scientists are
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  building new telescopes like 1 called Plato, which is launching
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  later this decade and is specifically designed to hunt
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  for Earth sized planets around sun like stars at Earth like
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  distances. And then there are even bigger
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  plans for future telescopes that would actually take photographs
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  of exoplanet atmospheres and look at what gases are in their
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  air. Because if you can see the air
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  around a planet, you might be able to spot what scientists
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  call biosignatures. Those are gases, or combinations
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  of gases that could hint that something living is making them,
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  like oxygen or methane. On Earth, most of our oxygen
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  comes from plants and tiny ocean creatures.
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  If you detected something similar around a distant planet,
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  that would be a very big deal indeed.
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  Some scientists have already found hints of interesting gases
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  around a couple of exoplanets, but these results are still
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  being debated and checked and double checked.
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  Science is very careful like that.
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  You can't just say we found aliens because you spotted 1.
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  Slightly unusual reading, although to be fair, that would
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  make for an incredible podcast episode.
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  So where does all this leave us? Well, we haven't found a true
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  Earth twin yet. No planet has been confirmed to
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  have Earth like air, Earth like temperatures, liquid water,
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  oceans, and signs of life all at the same time.
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  But here's why most scientists think other Earths almost
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  certainly do exist. Our Galaxy, the Milky Way,
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  contains hundreds of billions of stars.
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  Many of those stars have planets.
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  Some of those planets are rocky. Some of those rocky planets are
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  inhabitable zones, even if only a tiny fraction of them end up
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  being genuinely Earth like, that tiny fraction of hundreds of
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  billions is still an enormous number.
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  The universe is simply too big and too full of planets for
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  Earth to be completely unique. You might even be part of the
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  generation that grows up to see it, The confirmation that
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  somewhere out there orbiting a distant star is a world with
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  clouds and oceans and maybe, just maybe, something looking
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  back up at the sky. Wondering the same thing?
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  Finn wondered from Edinburgh, Scotland.
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  Are there other Earths out there?
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  Right before we go, it's quiz time. 3 questions.
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  Think carefully. No peeking at your notes and
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  definitely no asking a parent because this is your moment to
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  shine. Question one.
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  What do scientists call planets that orbit stars outside our
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  solar system? Is it a extravagant planets, B
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  exoplanets, or C extremely far away?
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  Very annoying little rocks. The answer is B exoplanets.
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  Exo means outside, so exoplanets are planets outside our solar
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  system. Extra credit if you chose C
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  though, because honestly, fair enough.
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  Question two. What is the nickname for the
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  region around a star where temperatures might allow liquid
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  water to exist? Is it a the Goldilocks zone, B
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  the warm and cozy corner, or C the habitable hammock?
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  The answer is A the Goldilocks zone.
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  Not too hot, not too cold, just right.
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  No bears required. Question three.
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  Scientists use the transit method to find planets.
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  What does this method involve? Is it A waiting for a planet to
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  send them a postcard, B detecting a tiny dimming of a
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  star's light when a planet passes in front of it?
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  Or C pointing a very large telescope at space and shouting
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  Is anyone there? The answer is B.
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  When a planet crosses in front of its star, it blocks a tiny
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  amount of light, and clever telescopes can detect that
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  flicker, although Option C is also something scientists have
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  tried to be fair. And that is it for today's
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  episode of the Curious Kid cast. We went from one kid staring out
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  the window in Edinburgh, Scotland, all the way to 6000
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  exoplanets, wobbling stars, Goldilocks zones, and the very
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  real possibility that somewhere out there is another Earth
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  waiting to be discovered. If you enjoyed this episode,
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  please share it with a friend, a classmate, A sibling, a pet
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  goldfish, or anyone else who has ever looked up at the night sky
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  and wondered what else is out there.
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  And if you subscribe, you'll never miss an episode, which
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  would be a tragedy of enormous proportions.
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  If you've got a question you'd like us to answer on the show,
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  head over to curiouskidcast.com and send it in.
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  It could be about space, animals, weather, food, the
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  human body, why adults always say we'll see when they clearly
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  mean no anything. We want to hear it.
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  I'm Charlie. Keep asking questions, keep
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  being curious, and remember the universe is absolutely enormous
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  and you are a tiny person on a tiny rock hurtling through it,
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  which is either terrifying or brilliant.
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  And I personally choose brilliant.