When you’re a subject as ancient as astronomy, you’re bound to build up a ton of myths.

I mean, yeah you’ve got  myths like how seven sisters became the Pleiades star cluster. But I mean “myths” as in “misconceptions”.

Like we can’t see the dark  side of the Moon from Earth. The dark side of the Moon is whichever half isn’t illuminated by the Sun at any given moment. And the only time we can’t see any part of that half is during a Full Moon.

You’re thinking of the far side. And yes, there’s about 40% of the Moon’s surface that we never see from down here. But that’s far from the only space myth out there.

We’ve pulled together 10 of the most common misconceptions, and we’re diving into just how wrong they really are… with a little help from one of  science’s greatest frenemies. [intro jingle] Not all myths are created equal. So we’ll be rating each of the  following myths according to our own, very unofficial Aristotle Scale of Wrongness Because Aristotle is famous for being wrong about a lot of things in science. And who doesn’t love a good 1 to 5 scale?

If a myth gets a mere 1 Aristotle, we’re mostly nitpicking. And if it gets a whopping 5 Aristotles, that’s like, "Everything in the universe is made from some combination of five elements”. Which yes, is a thing Aristotle actually believed.

So let’s dive in with Myth number 1: That Polaris, a.k.a. the  North Star, is super bright. If not the brightest star in the night sky, it’d surely make a year-end Top 10 list, right? Well, for one thing, Polaris isn’t even one star.

It’s actually three separate  stars in the same system. They’re just so far away from us, they blur into one dot without a telescope. But even then, the system doesn’t really stand out among the sea of stars in the night sky.

I can understand why you might expect otherwise. As the famous…if only temporary… North Star, Polaris has been super important for stuff like navigation for centuries. If it weren’t bright, it wouldn’t  be very helpful, would it?

Well the Polaris system barely breaks the top 50 brightest stars in the whole night sky. And the brightest star, Sirius, is a whopping 25 times brighter than Polaris. Although fun fact, there’s also more than one star in the Sirius system.

It’s got one regular star, and one white dwarf… the very very hot leftover core of a dead star. But before we give this myth any Aristotles, I should mention that the  brightest star in Polaris is more luminous than the  brightest star in Sirius. That means it’s pumping out way more light.

But because Polaris is further away from us, that light spreads out more as it travels, and the star looks less bright. So in the end, we’re going to give this myth 3 Aristotles. It’s technically true from  a certain point of view, but not in the way most people mean.

Our next myth is that water and organic matter are super rare in space. It’s a 2-for-1 deal! Water is actually a pretty common substance throughout the universe, because its two atomic ingredients… hydrogen and oxygen… are pretty much everywhere.

Hydrogen is the most abundant element in the universe, and oxygen is so readily made by stars that it’s the third most abundant… although it is a very distant third. Astronomers have spotted water ice on bodies in our solar system you’d never think to look, like Mercury. You know, the closest planet to the Sun.

But in its solid form, water is way more common past the so-called snow line, where the Sun’s light is diffuse  enough to let ice build up.   We’ve also seen water vapor in places like interstellar clouds, and the atmospheres of planets beyond our solar system! But liquid water is another story. When astronomers find liquid water somewhere, it’s still a pretty big deal, even when it’s not on the surface of a planet.

The search for liquid water is tied to the search for extraterrestrial life. As is the search for organic matter, the second half of the myth. But it’s a myth because in chemistry, the word “organic” does not equal life!

Instead, it can mean the building blocks of life, or the building blocks of  the building blocks of life… or just the very broad category of molecules that are carbon-based and  have nothing to do with life. And astronomers have found a bunch of different carbon-based molecules not just on other planets and asteroids in our solar system, but in the disks of matter surrounding other stars that will eventually turn  into planets and asteroids… …And also just floating around in space between solar systems! With all that said, I’m going to rate this pair  of myths... 4 Aristotles.

Myth number three: the Sun is a big ball of fire. If you think this, you’re in good company. Scientists thought that up through the 1800s.

But eventually, some of them actually did the math and figured out a Sun-sized  ball of fuel would only burn for about 3,000 years. And while they may have not known exactly how old the Earth really was by that point in history, they knew it was a lot older than that. The fire we’re familiar with down on Earth is a  form of chemical combustion, where oxygen reacts with other molecules and produces heat, light, and some leftover chemical byproducts.

But the Sun doesn’t consume its  fuel using a chemical reaction. It’s a nuclear one. Specifically, nuclear fusion… smushing atoms together under  intense heat and pressure, and releasing energy and light in the process.

No oxygen required. So, the sun isn’t a campfire, it’s a glowing ball of plasma! And as for the myth, it gets the honor of being the first one on this list to get a full 5 Aristotles.

Hooray!... I guess? You might not have heard anyone  repeat our next myth at a party.

But if you’re a fan of Science Fiction, you’ve definitely seen it. It’s that nebulas are so thick you can hide a spaceship in them. A nebula is a cloud of mostly hydrogen with a smattering of other elements.

And yeah, those particles are definitely packed more densely than the space outside the nebula. But at most, you’re looking at about 100,000 particles per cubic centimeter. That’s absolutely nothing compared to Earth’s atmosphere, which has about 10 quintillion  particles per cubic centimeter!!

And you may have noticed that you can see through the Earth’s atmosphere pretty well on an average day. At least a few kilometers. So if you were inside a nebula that’s over a hundred trillion times thinner, you could definitely see the alien spaceship that’s trying to sneak up on you.

But if that’s true, then why does every photo of a nebula make it look so thick, colorful, and soupy? Well, it’s because you’re looking  at a light-years big 3D object flattened into two. Imagine you’re stacking slices of the hole-iest swiss cheese you’ve ever seen in your life.

A few slices in, and there’s probably still a spot or two where you can see through the whole stack. But with enough layers all  the holes are covered up! So in the end, we’re looking  at another 5 Aristotles, folks.

And now I’m hungry…: so let me go shove some cheese in my mouth. I’ll be back! This SciShow video is supported by

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Mi chiamo Stefan Then, in as little as three weeks, you’ll be able to start having real conversations. You can start today at the link in the  description or by scanning the QR code   to get 60% off your Babbel subscription  with a 20 day money-back guarantee. Next up, the myth that outer  space is freezing cold.

If you’re talking about  the vacuum of space itself, well, it really has no temperature. Because it’s nothing…or as close  to nothing as nature can make. But there’s more to talk about, here.

Because it is true that many things floating around in space are very, very cold. Like the outside of the  International Space Station, which can get as cold as -160 degrees Celsius. But while it’s under direct sunlight, the ISS can also get very, very hot… up to 120 degrees Celsius!

Some of it has to do with how  close you are to the nearest star. Mercury is way closer to the Sun than the ISS, so during the day surface  temps can climb to 430 Celsius. But at the exact same time, Mercury’s backside has plunged to -180 because it has basically no way to trap that heat.

So in the end, I think we’ll give this myth a solid 3 Aristotles. It’s true some of the time,  but definitely not all. oh and fun fact: the coldest temperature in the known universe isn’t even in outer space. It’s actually in a lab on Earth!

But let’s rewind back to when I said “the vacuum of space”. Because that invokes another common myth: that space is a vacuum, so sound can’t travel through it. Or as one movie tagline put it: “In space, no one can hear you scream”.

Now, nowhere in space is it a pure vacuum. Every cubic centimeter of space is filled with fields and photons and individual particles of gas and dust… even if it’s way, way less dense than the air you scream through on Earth. And that means there are some places where sound waves can travel.

Although scientists like to call them “acoustic waves” in the literature. For example, there’s one black hole at the center of a large cluster of galaxies disturbing the matter around it. It’s creating ripples that would correspond to a note 57 octaves below middle C… the lowest note in the known universe!

Meanwhile, if you were in a spacesuit, floating in space and trying to scream for help, you could get someone to hear you if they were floating in a spacesuit next to you. All you have to do is make your helmets touch. That would transfer at least some of your scream over to their ears.

But really, you should use what basically all space-based communication relies on these days: a piece of technology that translates sound waves into radio waves, which are a type of light and can travel through a pure vacuum just fine. I’d give this myth 2 Aristotles, but you might be able to bribe  me with chocolate down to 1. Because I do admit it is a bit nitpicky.

Myth number seven: this is  a photo of the Milky Way. Humanity doesn’t have a single photograph of the Milky Way from a top-down perspective. Over the past seven decades of spaceflight, we’ve barely managed to send a spacecraft outside our solar system.

And our galaxy is over a hundred thousand times bigger than that. We are inside the Milky Way, so as far as you or I are concerned, it will only ever look like this. Or this, if you’re a scientist  trying to turn an image of the whole, spherical sky into an oval.

Note I said “image”. The fancy telescopes most astronomers use don’t really take photographs  in the traditional sense. But that’s a bit too semantic even for me.

Still, astronomers can use these images to figure out what the Milky Way should look like from an alien bird’s eye view. For example, the fact that we see the Milky Way as a stripe clues us into the overall disk shape. And by collecting very precise measurements for a bunch of different stars… not just where they are in the sky , but how far away they are… we can infer the Milky Way’s  classic spiral structure.

So at best, you have a model of the Milky Way made with a sophisticated computer program starting from a limited dataset and using the known laws of physics to fill in the blanks. At worst, it’s an image of a totally different spiral galaxy that’s labeled as the Milky Way. But most often, you get something in-between: an “artist’s concept” of  what our galaxy looks like based on the few important features scientists have learned are there, and similar spiral galaxies for reference.

So what’s this myth get? 5 Aristotles, no question. But let’s move onto a myth  that’s a bit more mind blowing: the Earth orbits the Sun. Or, more generally, all of the planets in our  solar system orbit the Sun.

And no, I am not a 17th-century pope who’s traveled forward in time to put you all under house  arrest for spouting heresy, like Galileo before you. That fundamental fact about the solar system that you learned as a child  is technically not true. Together, all of the planets and the Sun orbit around a point in space called a barycenter.

That’s because any object with mass has a gravitational pull, so it’s not just the Sun that’s  keeping all the planets in line. Each planet tugs a little on the other, but also on the Sun itself. And since everything in the solar system is moving at its own pace, the position of that barycenter  is constantly shifting, too.

Sometimes, our solar system’s barycenter is inside the Sun. But right now, it’s actually outside of it. Just some seemingly random  spot in not-quite-empty space.

This is so nitpicky, it’s definitely a 1-Aristotle kind of myth. But it’s an important nitpick, because the fact that planets and stars orbit a barycenter is how  we found the first planets outside our solar system! Basically, because a star with at least one planet has to orbit a barycenter, it appears to wobble in the sky.

And astronomers can track that wobbling to estimate both the mass of a planet and the size of its orbit! But sticking with planets… What’s the closest planet to Earth? Did you say “Venus”?

Well, you might be wrong. You might not be. While we were writing the script for this episode, the closest planet to Earth was Mars!

Although when we uploaded it to YouTube, it went back to being Venus. But if you’re watching this on, say, August 1st, 2025, it’s now Mercury! Personally, I blame this myth on all the placemats and school posters that show  the planets lined up in a row.

Because that almost never happens. The planets in the solar system all orbit the Sun at different rates. So the distance between any given planet and the Earth is always changing.

But maybe now I’ve got you wondering if Venus is the closest planet to Earth on average? No, that honor goes to Mercury! Mercury has the tightest orbit around the Sun… or should I say barycenter.

That means Venus gets a lot  closer to Earth than Mercury, but it also gets further away! So on average, Mercury wins out. In fact, Mercury is actually the closest planet to literally every planet in the solar system for the exact same reason!

So if Venus is only the closest  planet some of the time, and not even on average, it deserves a good ol’ 3 Aristotles. For our final myth, let’s get a little more down to Earth. Not quite all the way down, though, because it’s about what causes stuff to burn up as it enters Earth’s atmosphere.

It’s not friction. And yes,  this myth is pervasive. We even found a document from the FAA that blames friction for the  re-entry burns on the Apollo capsule!

Now, friction is technically an issue during your descent through the atmosphere. But it’s only really significant when you’re close to Earth’s surface. For spacecraft and meteor showers, the “burning” happens at higher altitudes, although it’s not really burning, and the physics of why it happens is much weirder than friction creating heat.

See, as an object enters Earth’s atmosphere, it slams into air molecules at such a high speed those molecules are able to knock bits of the object off. And when those still very speedy bits collide with even more air molecules, they wind up creating a plasma. Yeah, the same phase of matter that the Sun is made out of.

And for very complicated plasma physics reasons, that plasma gets so hot it can erode… or “burn up”...whatever it’s touching. In the end, I think it’s safe  to give this myth 4 Aristotles. But we’re not at the end of the list, yet.

Before I go, I’m going to  leave you with one bonus myth: The Sun is yellow. We talked about the color of  the Sun in a previous video, so you should totally watch  that one for more info. But basically, the Sun is white.

Yellow is just one color  of many that the Sun emits, which you can see by using a handy dandy prism… or a CD if you have one lying around. Really, if you want to refer to the Sun as any color other than white, it should be green, because that’s the color it emits the most. But I get it, the atmosphere  can make the Sun look yellow, so I’ll give it…I don’t know…3.5 Aristotles.

There are loads of other astronomy myths and misconceptions out there, but this episode is long enough. So feel free to share any  favorites that we missed. Maybe one day, we’ll make a Part 2! [outro]