This is our solar system.
Well, it's a model
of our solar system.
Sun at the centre and the eight planets that orbit it.
Wait a second.
What's this?
Pluto.
What are you doing here, Pluto?
Pfff!
(PLUTO CHITTERS INDISTINCTLY) (GASPS)
What? (PLUTO CHITTERS)
Well, don't look at me like that. What do you want me to do?
You're technically not a planet anymore, you're a dwarf planet.
But that doesn't mean you're not important.
Oh, Pluto, your discovery was very important.
And it led to us learning even more about our solar system.
(PLUTO CHITTERS) Yeah, that's right.
Let me explain, but let's go back a bit.
It was the ancient Babylonians
that first observed the planets in our solar system.
They noticed that while most stars stayed in the same position
relative to each other, some of them would move around the sky.
They weren't stars at all.
They were planets.
In fact, the word 'planet' comes from the Greek word 'wanderer'
because they...wandered through the sky.
At first we thought there were only five planets:
Then in the 16th century,
we realised that Earth was also a planet.
Yep, mind blown.
It was Nicolaus Copernicus in 1543
that suggested the planets revolved around the sun.
It took a few years to catch on,
but eventually people accepted the idea.
About 200 or so years later, we discovered Uranus.
(PLUTO CHITTERS) Hey!
No jokes, please, Pluto.
(PLUTO TITTERS) Cheeky.
Like the other planets, you can see Uranus without a telescope.
Because it's quite dim and moves very slowly,
no-one really noticed it,
until 1781, when astronomer and composer Frederick William Herschel
came along and discovered it.
Then in 1846, astronomers noticed
something weird happening to Uranus's orbit?
Turns out it was because of the gravitational pull
of Planet eight, Neptune.
And that brings us to Pluto.
In 1930, American astronomer Clyde Tombaugh
was checking out images he'd taken of the stars
and realised one of those specks of light kept moving.
Pluto's discovery made headlines.
Its name was actually suggested by an 11-year-old
who thought it would be cool
to name it after the Roman god of the underworld,
seeing as Pluto lives
in such a cold and desolate part of the solar system.
Then we spent the next few decades
remembering the names of all nine planets in our solar system,
until...
Yep, Pluto, my friend, you were downgraded to a dwarf planet.
I mean, you are pretty small compared to the others.
Especially that one, and that one.
And that one.
Well, all of them, really.
You're actually smaller than our moon and Australia.
Yeah, you're pretty tiny.
Plus, we've found a bunch of other objects in the solar system
that are much bigger than Pluto,
but not quite big enough to be planets.
In 2016 we sent this spacecraft to study Pluto,
found out it had a bunch of moons, and, best of all,
had a big old love heart on its surface.
Aw!
So, to some of us, you'll always have a special place in our solar system.
Just, uh, not this model because, you know, accuracy.
Yeah.