It never gets dark anymore. Not REALLY dark, anyway. Not like it used to. Light pollution is not only making it more difficult to see the night sky, but it's also affecting our health. For the past century and a half, since the dawn of...

Having bones is pretty cool. They make our blood, let us hear, and keep us from being just a squishy puddle on the floor. But for every species with bones, there are at least 20 species on Earth with exoskeletons instead. And those...

A human with the metabolism of a hummingbird would need to eat about 80,000 calories a day to survive. That’s because staying warm by making your own heat takes a ton of energy. And that brings up a paradox, because creating your own...

You may have heard that a kilogram of feathers weighs the same as a kilogram of steel, but that all depends on where you weigh them. This video is all about the difference between mass and weight, and how weirdly awesome Earth’s gravity...

A massive new study has just been released showing that human activities are threatening Earth’s other life forms in some very bad ways. One million species may be at risk of extinction. Just let that sink in. Isn’t the Anthropocene...

There’s a lot of confusion out there about what is and isn’t a dinosaur. And you’d be forgiven for being kinda confused. Maybe paleontologists are just messing with us. Or… maybe the question of what is and isn’t a dinosaur goes deeper...

Why are trees and other plants green? Seems like a simple question. But the answer is full of surprises. Using a special camera that can pick up light just beyond the visible range, into the near-infrared, you’ll get to see trees like...

The monarch butterfly migration is one of nature’s greatest events. This orange-winged wonder travels up to 4,500 km from all over North America to spend the winter hanging from oyamel fir trees in central Mexico’s mountain forests. I...

Greetings, fellow Homo sapiens. Our species is the only remaining member of the genus of upright, walking apes known as Homo. Where did we come from? Our history just got a whole lot more complicated (in a good way) thanks to some...

The largest pterosaurs like Quetzalcoatlus were closer in size to airplanes than birds. No flying animal alive today comes close to their huge size. So did giant pterosaurs actually fly? I went to see the fossil bones of the largest...

I met Molly Burke a few months ago. She’s awesome. I absolutely love what she’s done on YouTube to bring awareness to living with disability, and turning it into ability. And her guide dog Gallop is awesome too! When Molly and I first...

Ever feel like you aren't totally yourself? Well, maybe you aren't. In this video, we explore the idea of human chimeras. In mythology, the "Chimaera" was a beast made from different animals combined into one. But in biology, a chimera...

Can trees really save us from climate change? For eons, nature has relied on photosynthesis as a big way to keep carbon dioxide levels from getting out of control. But as we have put more carbon into the air, we’ve also cut down many of...

Fifty years ago, we sent the first astronauts to walk on the moon’s face. But what they brought back is just as important as what got them there. I’m talking about moon rocks, guys. And I got to go visit NASA’s lunar sample vault to...

It sounds like such an incredible fact. “Our own cells are outnumbered by our microbes 10 to 1!” I don’t remember where I first heard it. But I read it in science papers and articles by journalists, so I believed it without question. I...

Earth has seasons, but what about the rest of the planets in the solar system? Let’s take a tour from Mercury to Pluto and see what seasons would be like on all our planetary neighbors. Bring a sweater!

Honeycomb. Strawberries. Flower pods. Some people find these things incredibly scary. We call this extreme fear trypophobia. But why does it exist?

The Apollo program was famous for being risky and expensive. It sent multiple daring astronauts to the moon, but had a crunched timeline, and lacked modern tech. In this special episode of SciShow, we'll be discussing... was the Apollo...

The women of Afghanistan are being persecuted under Taliban rule, but they're not standing down. Filmmaker Tamana Ayazi chronicles the harrowing reality of one women's rights advocate -- Zarifa Ghafari, Afghanistan's youngest female...

It's Craig's last episode of Film and in it he's going to talk about weird stuff... and real stuff. Experimental and Documentary films could each take up their own Crash Course series. The different styles and intents of different...

There are a whole lot of people out there who have bought into the notion that, in order to be physically fit, you should aim for taking 10,000 steps a day. But where did this idea come from, and how did we all agree on this magical,...

Vanessa Hill of BrainCraft shares her science YouTube story with Hank and reveals a big announcement! Jessi from Animal Wonders and a special Australian friend or two join in the second half.

During our Film History and Production series, we talked about how Film is an "Illusion of Reality." That filmmakers use shots, cuts, and narrative structure to trick us into believing what we're seeing. But, what happens when that...

In which we continue our exhaustive look at One Hundred Years of Solitude by Gabriel Garcia Marquez.