Hi, and welcome to Brain Stuff.
I'm Jonathan Strickland.
And I'm Ben Bowlin.
And Ben, I understand we have an interesting question today.
Oh, yeah.
This is a good one.
All right, so Jonathan.
Are you ready?
Yep.
That's not the question.
OK.
All right.
How do astronomers measure distance?
How are they able to measure how far away a star is?
Ah, right.
So it turns out that measuring the distance to the star
is an interesting problem.
So astronomers have come up with two different techniques
to estimate how far away any given star might be.
Now, that first technique involves
triangulation, or parallax.
So the Earth orbits the sun, right?
Yeah.
Well, as it orbits that sun, there's
a diameter of orbit about 186 million miles.
So by looking at a start one day and then, maybe,
six months later, looking at it again?
Astronomers can see a difference in the viewing
angle for that star.
So with a little trigonometry-- which is, frankly,
terrifying to me-- the different angles yield the distance.
So this technique works for stars
that are about 400 light years away from earth, or closer.
Now, there's no direct method currently
available to measure the distance
to stars that are further than 400 light years from Earth.
But there's an approximation, right?
Yes.
And this is a pretty clever one.
This is the second technique.
Astronomers can use brightness to figure out
a star's distance.
So they do this because it turns out
that a star's color spectrum is a good indication
of its actual brightness.
So like blue, white, et cetera.
The relationship between color and brightness
has been proven using the several thousand stars that
are close enough to Earth to have their distance measured
directly, that would be the 400 light years and closer.
So astronomers can look at a distant star,
determine its color spectrum.
And from the color, then they can
determine the star's actual brightness.
By knowing the actual brightness and comparing it
to the apparent brightness seen from Earth-- that is,
by looking at how dim the star has actually become
once its light reaches the earth,
they can determine that the distance of the star
is whatever it happens to be.
Right.
And there's some other stuff we should probably talk about.
Yeah.
I've got some trivia for you, Ben.
Oh, good.
OK.
All right, so let's talk about some of the astronomical units
that astronomers use, including the astronomical unit.
So the astronomical unit refers to the distance between Earth
and the sun, the average distance.
It's about 149 million kilometers or something.
Then you've got the light-year.
Yeah, what is a light-year?
So, a light-year is like a regular year
but with fewer calories.
Heh.
Actually, of course, the light year
is the distance that light can travel
through the vacuum of space within the span one Earth year.
So that's pretty big, because light's pretty fast?
Yeah, yeah.
We're talking just under 10 trillion kilometers.
That's a pretty long distance.
But I've got something that's even longer than that.
And that is a parsec.
Hang on.
Is this a Star Wars reference?
It can be.
But, all right, so, Parsec in Star Wars
sounds like it's a unit of time.
It's actually a unit of distance.
And the way it works is you talk about the distance
between our sun and some other astronomical object that
has a 1-second arc degree difference in parallax angle.
Now that essentially means that when we look at the star
and we compare it to the sun, and we
do that again at another point on the Earth's orbit,
we get that 1-second arc degree.
That distance actually ends up being 3.26 light-years.
So it's even longer.
So there you go.
Astronomical units.
Wait.
So the Kessel Run--
We'll get to it.
Meanwhile, while you guys have enjoyed this video,
you should show your love to us by liking it,
and then subscribe to the channel.
We've got a lot more questions we're
going to be answering, like the Kessel Run.
Thank you.
So Ben, the Kessel Run is, in fact,
a smuggling route in the Star Wars universe.
Now, the retconned explanation of why
Han Solo refers to the parsecs is
that this route goes through several black holes.
And for a ship to be safe, it has
to go around the black holes as much as possible.
So the safest route is probably around 15 parsecs.
But Han Solo?
He's a daredevil.
And so he cuts off several parsecs
and makes it more of a 12 parsec or less than 12 parsec run.
Oh, that's the line.
Yeah.
But is that because of the Force, or something?
No.
Han Solo doesn't believe in the Force.
He's all skill, man.
It has nothing to do with some--
It's been a long time since I watched Star Trek.
So I don't really, I don't know.