- [Chuck] This episode of Wheel of Science
is brought to you by Wix.
- This week, on Wheel
of Science, cannabis!
Nah, actually it's space stuff.
- Yeah, Chuck, we're
talking solar system stuff,
on Wheel of Science.
(upbeat theme music)
- Hey, everybody, I'm Chuck Nice,
and welcome to Wheel of Science,
the interactive show where we answer
your questions about the universe.
I don't answer your
questions about the universe.
The one, the only, Dr. Neil deGrasse Tyson
answers your questions about the universe.
What's up, Neil?
- All good, Chuck.
All good in the universe.
It's Earth that's messed up.
- So Neil, you're beaming
in from San Francisco, huh?
- Indeed.
- Yeah, I had an uncle who
actually escaped from Alcatraz.
- No you don't, and no he didn't.
- Of course I'm lying, yes.
All right, you ready to jump
into our first question?
- All right, bring it on.
(wheel spinning)
- Malik Maaz wants to know this:
Why does gravity produce
elliptical orbits?
Why aren't they perfectly circular?
What's up, Neil?
- Well, all gravity really does is change
the path that you would have otherwise
taken though space.
I'm trying to go in a straight line,
and something down here's got
some extra gravity for me,
I end up curving towards that object.
But if I have high enough speed,
my trajectory will curve,
but it won't get pulled into orbit.
It'll just sort of send it
in a different direction.
And if I don't have enough speed,
it'll curve me so much,
I'll come in and crash.
It's only in between those two extremes
that you end up having
any kind of orbit at all.
You can have all kinds of orbits,
depending on what kind of speed you have
and what your distance is.
Comets typically have very
elongated oval orbits, like that.
And planets, as we think of them,
tend to have much more circular orbits,
but they're still ellipses.
There's a little known fact,
that over enough time,
the interaction between
the object and the host,
it could be a moon and a planet
or a planet and a star.
Over time, the orbit becomes
more and more circular
in their interactions.
And depending on how close it started,
and what the thing is made of,
that can happen quickly.
You can end up with
a perfectly circular orbit eventually.
But otherwise, gravity's just something
that changes your direction.
That's all.
- [Chuck] So maybe
that's why Pluto's orbit
is different than any other planet.
(gasps) Did I say planet, Neil?
Oh, I'm sorry.
- Its orbit is so elongated,
it crosses the orbit of Neptune.
That ain't no kind of
behavior for a planet.
I'm just saying.
- [Chuck] I'm joking, Neil,
I'm joking.
- You don't wanna go there.
- All right, you ready
for another question?
- Yeah, spin the wheel.
(wheel spinnning)
- [Chuck] Matt Hairfield wants to know
why the planets orbit in
the direction that they do,
or is it a 50/50 chance?
- An answer to that question
was first posed more than 250 years ago.
In mid-1700s, Immanuel
Kant, the philosopher,
as well as Laplace, a French
mathematician physicist,
proposed something called
the Nebular Hypothesis.
'Cause how else do you get all the planets
orbiting in the same direction?
Who ordered that?
And it turns out, if you have a gas cloud,
that is the parent object
that becomes the star
and its orbiting planets.
And this gas cloud rotates,
as everything does in the universe,
and it's out of that gas cloud
that you make your planets, and moons,
and other objects,
then anything you make
out of that gas cloud
is gonna have an orbit
in the same direction
around the host star.
And the star will be rotating
in that same direction.
So, this was an idea 250 years ago,
later on, more thought invested in it,
computer models, bears this out.
And so, that's how you can have
an entire family of objects,
everybody going in the same direction.
And in fact, so strong is
that concept and that idea,
that if you find something
orbiting the other way,
you probably captured it later,
and it did not have anything to do
with the formation of the system itself.
That's how you know who's got
birth right to the system,
and who came in later.
- [Chuck] As usual, Neil, (popping sound)
That was a little mind blow.
That was just a little one, okay?
- That's all I did to you?
- Hey look, we gotta take a break,
but when we come back,
we're gonna take a look at some comments
from the Wheel of Science group,
and of course, take more questions.
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Welcome back to Wheel of Science!
You know what time it is.
- No, I don't.
What time is it?
- Time to spin that wheel!
Remember, all these questions come from
the Wheel of Science Facebook group.
Erin Kennedy wants to know this:
Could you please explain the significance
of the heliosphere, and how it's made?
- [Neil] So the sun, as we know,
is a ball of gas,
but it's not just all stays that way.
Some gas gets, like, ejected.
And so there's a stream of particles
that come from the sun
that we call the solar wind.
And you might have
heard of the solar wind,
'cause it makes aurora.
The particles stream and collide
with our atmosphere near the poles,
and it renders it a glow.
Very beautiful.
Well, this solar wind moves
completely through the solar system,
and it goes beyond the planets,
beyond the comets,
and there is a point,
where this solar wind
can no longer be distinguished from
the median that permeates between
the stars of the galaxy.
That is the actual edge
of the sun's influence.
The sun's sort of particle influence
on its environment.
And we call the size of
that volume the heliosphere,
and the boundary of that
volume the heliopause.
And on September 12th, 2013, Voyager One,
the intrepid Voyager One,
crossed the heliopause,
and only then could you say,
it has left the solar system entirely.
It's not just, oh, let's
go beyond the last planet,
and now you've left the solar system, no.
No, the sun reaches out far beyond.
And there you have the heliosphere.
And it's always there, by the way.
And as we move through the galaxy,
it can take on different shapes,
depending on what's going on around us,
and depending on the strength of the wind
at any given moment.
So it could be a sphere,
but it's usually a teardrop,
as the solar system moves,
as we orbit the center of the galaxy,
the Milky Way galaxy.
Do you have it, Chuck?
- All right, Neil, that's the heliosphere,
but can you answer this?
What is the craposphere?
No you can't, 'cause I just made it up.
It's my life.
- I got nothing for you on that.
- All right, now, on a serious note,
you know we did an
episode about asteroids,
and I actually saw this comment
in the Facebook group comments.
Ray Parker said this:
I don't care or want to
hear about asteroids.
If we get hit, so be it,
nothing we can do about it.
There are other things
that are a lot more important than rocks.
Neil.
- [Neil] This is why you want
scientists and engineers in your midst.
Because when something that might
render you extinct arises,
is on its way towards Earth,
they will look up and say,
how can we prevent that?
And they'll use methods and tools,
and ingenious ideas,
and that can be the difference
between you being alive,
saying you don't care,
and you being extinct,
where your thoughts then
wouldn't matter to anyone.
- [Chuck] Hey man, nobody
can argue with that.
I'm picking the reality where
my president is Morgan Freeman!
And now I have a question
for all of you watching.
Elon Musk announced the first
commercial flight around the moon.
Would you want to be on that trip?
Answer the poll, right now.
I don't wanna be on it.
I'm not being on that.
Thanks again to Wix.com for bringing
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As always, thanks to Neil deGrasse Tyson.
Thanks, Neil.
- You know I love you, Chuck.
- I love you too, man.
That was weird.
Hey, I'm Chuck Nice, and until next time.
This is Wheel of Science.
(upbeat theme music)
