Misconceptions about Space - mental_floss on YouTube (Ep. 38) | Mental Floss

Hi, I'm Elliot and this is Mental Floss on YouTube

Today I'm going to talk about some misconceptions about space. So I hope you like NASA, because we're going to be talking a lot about them today

Misconception number one, the sun is on fire. When many people picture the burning sun, they imagine something much like a campfire or an object on fire

But the sun is actually a ball of gas. It burns thanks to nuclear fusion, which happens in its core

What that means is every second 700 million tons of hydrogen gets converted into 695 million tons of helium

When this happens, energy is released as gamma rays which get converted to light, so it emits light and heat, but it's not on fire

In order for it to be considered on fire, there would have to be oxygen involved, and there's not

Misconception number two, the Sun is the only star that has planets. Experts now believe that most of the stars in our Milky Way have planets surrounding them

Any planet that's found outside of our solar system is known as an exoplanet

and we can be pretty sure that they exist because they affect the way a star looks

One of the most common methods to check this is to look for a decrease in light from certain stars during various times which would indicate that a planet is orbiting it affecting how the light appears to us Disconception number three Mercury is the closest planet to the Sun so it the hottest Actually distance from the Sun has little to do with average temperature on a planet

Venus is actually the hottest planet in the solar system, but that's because of its atmosphere

The atmosphere contains mostly carbon dioxide and a little bit of nitrogen, making it very thick

Throughout the year, the surface of Venus remains at a temperature of about 462 degrees Celsius

The surface of Mercury, on the other hand, has a lot of temperature variation. It can be as cold as negative 173 degrees Celsius at night, and during the day, it might reach 427 degrees Celsius

Mercury has a very thin atmosphere, which is why there's so much variation in temperature

Misconception number four, people explode in space. Space is a near vacuum, which means that people can't survive there for more than a couple minutes

But exploding isn't a concern. A body exposed in space will expand and bloat, especially the air in the lungs and the water and body tissue

But human skin is actually tight enough to prevent exploding. A person exposed to space would eventually die when circulation stops after dissolved gases in the blood form bubbles and block flow

Basically, it's like an extreme version of the bends that divers get

But they don't actually explode, so just know that. Misconception number five In the 60s NASA spent millions of dollars developing a pen that would write in space So this is a popular myth on the internet in even one episode of the West Wing People tend to use this as a comparison between NASA and the Soviet astronauts who were smart

enough to just bring pencils. But NASA used pencils as well, and they have the receipts to prove it

In 1965, NASA placed an order for 34 mechanical pencils from Houston's TICAM Engineering

Manufacturing Incorporated. There was an independent company, the Fisher Pen Company, that developed a space pen for

around a million dollars. And later, both NASA and the Soviets started using Fisher's anti-gravity space pen

Because it was a great pen. Speaking of gravity, misconception at number six. In space, you experience zero gravity

Gravity is actually considered the most important force in the universe, and it doesn't just go away when we leave Earth

Thank goodness. Gravity is necessary for everything from the moon's ability to orbit the Earth to the sun

staying put in the Milky Way. What astronauts actually experience in space is what NASA calls microgravity

It has nothing to do with the actual strength of gravity, which is only very slightly less

on the space station. It's because astronauts are constantly falling, so they seem weightless

Misconception number seven, black holes are like vacuums. As we learn more and more about black holes

experts are more likely to compare them to Venus fly traps than vacuums

Basically, they don't suck up every object nearby. Instead they sit pretty dormant Then if a star approaches it and gets too close the black hole becomes active And still only some of the objects nearby get ripped apart by the black hole You can sometimes go through them and come out another one

to a different part of the universe, or at least that's what I learned in interstellar

Misconception number eight, the moon orbits the Earth once a day. It takes about 27.3 days for the moon to orbit the Earth

This is known as a sidereal month. Though it's worth noting that the moon's orbit

isn't considered regular. It has variations and there are upwards of five different months that astronomers recognize

And that brings me to misconception number nine. There's a dark side of the moon

As the moon is orbiting the Earth, it's also rotating on its axis, so we're always seeing

the same side of the moon no matter what. But the opposite side isn't dark. It gets the same amount of sun as the other side

Misconception number ten, a light year measures time. It actually measures distance. NASA defines a light year as the total distance that a beam of light moving in a straight line

travels in one year. Light travels at around 300,000 kilometers per second, so a light year is around 10 trillion kilometers

watching Misconceptions on Mental Floss on YouTube. If you have a topic for an upcoming Misconceptions episode that you would like to see, please let us know what it is in the comments

down below, and I'll see you next week. Bye