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So you know what a star is, right? Well, if you don't, you should. We've talked about that big one in the sky a few times: The Sun! But there are a lot of bright dots in the night sky and not all of them are stars. Today, let's play a game of "Star or Not a Star" to learn a little more about everything that's up there.

This first series is based on 5th-grade science. We're super excited and hope you enjoy Crash Course Kids!

///Standards Used in This Video///
5-ESS1-1. Support an argument that differences in the apparent brightness of the sun compared to other stars is due to their relative distances from Earth. [Assessment Boundary: Assessment is limited to relative distances, not sizes, of stars. Assessment does not include other factors that affect apparent brightness (such as stellar masses, age, stage).]

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Producer & Editor: Nicholas Jenkins
Cinematographer & Director: Michael Aranda
Host: Sabrina Cruz
Script Supervisor: Mickie Halpern
Writer: Kay Boatner

Executive Producers: John & Hank Green
Consultant: Shelby Alinsky
Script Editor: Blake de Pastino

Thought Cafe Team:
Stephanie Bailis
Cody Brown
Suzanna Brusikiewicz
Jonathan Corbiere
Nick Counter
Kelsey Heinrichs
Jack Kenedy
Corey MacDonald
Tyler Sammy
Nikkie Stinchcombe
James Tuer
Adam Winnik

Venus Image Credit: Brocken Inaglory
(CrashCourse Kids intro plays)

Sabrina: What makes a star? Is it the right hairdo, a funny twitter account, cool clothes, famous friends? Well if you're into science like I am then the stars you should care about aren't the ones in movies or on TV, they're the ones in space.

But with so many shiny objects floating around up there, it can be hard to tell what's a star and what's not. So, let me introduce you to some real stars.

A star is a bright object in space that gives off light through energy that it makes in its core. Now hmmm... something really bright that gives off a lot of light, and it creates energy in its core. That sounds familiar. And if it doesn't, it should. I'm thinking of the sun.

We already learned that the sun is a star. Like the sun, all stars are giant balls of gas located millions of kilometer away from us. Obviously the sun isn't the only star in our universe, it's just the most famous one, at least to us.

Astronomers think that there are billions of stars out there, but does that mean all the sparkly things you see when you look up at the night sky are stars? Nope.

There are all kinds of things in space that glow- or appear to glow- just like stars do. But they're not actually stars. Let's check out three kinds of things in space that can sometimes get mistaken for a star.

First up, planets. Planets are big round objects in space that travel around a star. You know, or really should know, that you live on a planet: Earth. There are seven other planets in our solar system: Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune. All of these planets travel around the same star: the sun.

These eight planets aren't the only planets in our solar system, though. There are several other planets up there too, but because of their smaller size scientists call them dwarf planets. Dwarf planets are a lot like regular planets.

They're roundish and also travel in a path around the sun, but unlike regular planets, dwarf planets are smaller and they might be in for a bumpier ride. While regular planets have a clear path around the sun, dwarf planets paths are full of other stuff like asteroids. More on those in just a minute.

So how can you tell planets and dwarf planets apart from stars? I mean it's pretty easy to mix them all up from a big distance, but if you zoom in really close, planets and stars are pretty different. Most planets appear brighter to us than stars do. This is because the planets we see are closer to Earth than the stars are. Another big difference is whether they appear to move in relation to the other things in the sky around them.

Like I said, the planets orbit or follow a path around the sun. So imagine that you observe a certain planet by taking photos of it in the sky for many months, and then you compared all of those photos. You'd be able to track the planet's movement and see that it's position in the sky changed in relation to the stuff around it.

Stars change their position in our night sky too, but they're located MUCH further away, so it's harder to track their movement. Plus, when stars move, because they're all so far away, they appear to all move together. So if you're tracking one star as it changes its position in the night sky, the stars around it move with it.

Another thing to look out for? Color. If an object in space has an intense color, it's most likely a planet, not a star. So besides planets and dwarf planets, what's the third object in space that could be mistaken for a star? Asteroids.

Asteroids are chunks of rock and metal that also orbit around the sun. Most asteroids are found in the asteroid belt, an area between Mars and Jupiter. So what does an asteroid look like? To a passing spacecraft, it just looks like a giant rock, but from a spot very far away like Earth, asteroids can look like tiny spots of light.

So how do you tell the difference between an asteroid and a star? Sort of how you tell the difference between a planet and a star. Like planets, asteroids are closer to Earth than stars and are easier to track across the night sky over time. Also, stars tend to twinkle when viewed from Earth, or blink on and off, going from bright to faint. Planets and asteroids generally don't twinkle.

Now let's take some of what we've just learned and see if we can spot the real stars among the imposters.

It's time to play: Star or Not a Star. Here's how it works: we look at an image of something in space and I'll give you some clues. Then you'll guess whether the object is a star or not. Here we go!

Introducing object number one. Star or not a star? Let's take a look at the evidence. Your first clue is brightness. Most stars aren't as bright as this object, meaning it's probably pretty close to Earth. Now let's watch the object for a couple of months. Just kidding. I'll just tell you that after watching this object for a very long time, you'd be able to tell it's moving through different parts of the sky night after night, while most of the stuff around it doesn't seem to be moving at the same rate.

So star or not a star? If you say that this is not a star, then congrats, you're a genius. Or you know, you've been paying attention. The object is one of our planet neighbors, Venus. Since it's a planet, it's much closer to Earth than the stars and therefore appears to be brighter. And since it's a planet, it's moving around a star, in this case, the sun.

OK. Object number two, star or not a star? This object isn't as bright, is it? If you were to watch it for a very long time it might appear to move, but it would still be surrounded by the same stuff you saw around it when you first started observing it. It would also twinkle, or look like it was blinking every so often. So star or not a star? Star! Yep, this pretty thing is a star called Enif, one of the brighter stars in the night sky and part of the constellation, or group of stars called Pegasus.

There's really no easy way to tell from Earth if a shiny object is a star or something else, but if you're willing to get out your telescope and be super patient, you can make an educated guess by looking at the object's brightness, if it twinkles or not, and if it appears to move in relation to stuff around it in the night sky.

So, to sum up, a star is a bright object in space. But now you know that just because something in the night sky is shiny, that doesn't automatically mean it's a star. Real stars make their own light, unlike planets and asteroids which just reflect light from other objects. So the real stars in the sky are the stars I care most about. They're all superstars if you ask me!