[♪ INTRO]
[Jessi] Hey, everybody! My friend Sam and I love learning about space.
[Sam] That’s for sure. I just love using my telescope to look at the stars.
[Jessi] And it seems like you guys love learning about space too.
In fact, you’ve sent us lots of questions about it.
[Sam] So Jessi asked me to help answer some of them today.
Are you ready to get started?
[Jessi] Let’s do it!
Paxton, age 5, asks: How do scientists use math in astronomy?
[Sam] I know that astronomers, the people who study stars and planets,
use lots of math in their jobs.
Lots of other scientists do, too.
[Jessi] Yep, math helps us do lots of kinds of science.
So, learning math helps us get better at science.
But what specific things do astronomers do, Sam?
[Sam] Well, sometimes, they need to know how far away things like stars and planets are in space.
[Jessi] That’s a great example of something they use math for!
You can use math to figure out just how far away a star is from Earth.
[Sam] Whoa, cool!
[Jessi] Here, let me show you.
You can do this at home, too!
Hold a pencil out in front of you, with your arm stretched all the way out.
Like this.
Cover your left eye and look at the pencil.
Now, uncover your left eye and cover your right instead, and look at the pencil again.
Go back and forth a few times… Here, you try, Sam.
[Sam] Ok.
[Jessi] Do you see it?
[Sam] Whoa! The pencil is jumping back and forth a bit!
[Jessi] It’s not really jumping, but it looks like it.
Now, I’ll put the pencil halfway closer to you and try it again.
[Sam] Woah, the pencil jumps a lot more now.
[Jessi] Yes, it jumps way more!
The reason the pencil looks like it jumps is because… well, you have two eyes.
Normally, they work together to make one picture for you to see.
But when you close one, you can see things from slightly different positions.
[Sam] That’s neat, but the pencil isn’t a star!
[Jessi] Astronomers do something really similar to figure out how far away a star is.
The pencil appears to jump more when it’s closer to you, and less when it’s farther away.
Well, stars can appear to jump too.
[Sam] Oh! Is that because… the Earth is moving around in space?
[Jessi] Yes! Every year, the Earth makes a trip around the Sun.
That means, at different times in the year, we are in a different place in space.
Just like your eyes give you two different points of view,
we can check stars at different times of year to see how much they jump.
[Sam] So a star that jumps a little is farther away, like when the pencil is farther away.
And a star that jumps a lot is close.
[Jessi] Exactly. And astronomers can do some math to figure out the exact distance!
But that’s just one example of how astronomers do math. There are many, many ways.
[Sam] That makes me want to get extra good at math, so I can get extra good at astronomy too.
[Jessi] I can’t wait until you’re discovering new stars and planets!
Or maybe you’ll solve even bigger mysteries. Like this next question!
Jane, age 4, asks: How was the universe created?
[Sam] How can we answer this question?
If the universe wasn’t created, then no one was there to see it, right?
[Jessi] You’re right, there were no people. In fact, there was no anything yet.
[Sam] No Earth… no sky… no planets or stars or anything at all.
[Jessi] That means scientists have to make careful guesses about what happened a long time ago,
based on what we can see now.
[Sam] So what can we see?
[Jessi] Well, you know what galaxies are, right?
[Sam] Yeah! A galaxy is a big group of stars.
The galaxy we live in is called the Milky Way.
But there are lots of star groups like ours out there in the universe.
[Jessi] Exactly! And if we look really closely at these galaxies… with really strong telescopes…
we can tell that most galaxies are moving away from us.
It’s almost like everything in the universe is flying apart.
A little bit like when you use a party popper and all the confetti goes flying out.
[Sam] So… the universe started off inside a party popper?
[Jessi] Kind of!
Scientists believe all the stuff that we can see in the universe now
used to be scrunched down in one tiny place… like confetti inside a party popper.
But then it all went flying apart, and the stuff in that tiny space grew and changed into stars
and planets and eventually, you and me. Scientists call that the Big Bang.
[Sam] That’s a really big bang.
[Jessi] The biggest!
[Sam] But what happened before that? Who popped the universe’s party popper?
[Jessi] We don’t know for sure!
And we might never know, since it came before… everything that we know of!
But scientists are still hard at work thinking about it. So maybe one day we’ll know more.
Let’s see… I think we have time for one more question.
But instead of being about the whole universe,
this question is about just one planet in our solar system.
Zasu, age 8, asks: does Venus have an atmosphere?
[Sam] I know what an atmosphere is!
On Earth, the atmosphere is a word for the air. All of it!
The atmosphere is like a blanket of air that wraps all around the entire world,
and reaches all the way to space.
[Jessi] Yes! Without our air blanket, we definitely wouldn’t
be able to breathe… or live on Earth at all.
So the question is, does planet Venus have an air blanket?
What do you know about Venus, Sam?
[Sam] Hmmm, Venus is the second planet from the Sun. It’s also our closest neighbor in space.
It’s a lot like Earth. Like, it’s almost the same size…
and it has an atmosphere, or air blanket, too!
[Jessi] It sure does. But… it’s not very much like our air blanket.
Our air blanket is made of invisible gases like oxygen,
which is nice to breathe and enjoy if we’re out stargazing on a warm summer night.
On Venus, you probably couldn’t see the stars… and you definitely couldn’t breathe the air.
[Sam] Man… there goes my Venus picnic idea.
[Jessi] Venus’s air blanket is different than Earth’s.
There’s a lot more of some kinds of gases, like carbon dioxide, that aren’t good to breathe.
Some of the gases even smell like rotten eggs!
And that means Venus’s air blanket would definitely hurt people if we visited.
In fact, we’ve sent spacecraft to Venus, and even they don’t last very long!
The atmosphere of Venus is very hot and very, very heavy.
[Sam] Air can be heavy? It doesn’t feel like anything.
[Jessi] I know! Air doesn’t feel like it’s heavy!
But our air blanket pushes down on us a little bit.
We just don’t notice because it’s there all the time!
Venus’s air blanket pushes down so much that you or I would be smushed if we went there.
And our spacecraft do get smushed.
[Sam] I don’t want to get smushed, so I think I’ll take my summer vacation somewhere else.
[Jessi] Thank you to everybody who sent us questions today!
You can ask a grownup to help you send your questions to us.
They can get started at patreon.com/scishow.
We’ll see you next time, here at the fort!
[Sam] Bye!
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