If someone (say, a small child) asks you why the sky is blue, you might dive into an explanation of Rayleigh scattering. But if you want to give them a way cooler explanation, you can tell them it's because of bacteria.



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The Sun isn’t the only celestial body in the solar system to boast spots of its own. Mercury, too, has its fair share, and they’re worth wondering about.

What color is a banana? Duh, it’s yellow. But what is yellow? Now that you mention it, how do we see color in the first place? That’s the series of questions that led me to making this video. It started simple and took me down a rabbit...

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...

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 Sun is green, actually. We'll go into why the blackbody effect means the Sun emits more green visible light than any other color, and why evolution and color perception mean it's ok to see it as yellow, anyway.

You might know that if you chomp on a Wint-O-Green Lifesaver in a dark room, you can see little blue flashes of light in your mouth. What you might not know is that this is an example of triboluminescence: a fascinating, somewhat...

Taking photos used to require technical knowledge and time in a lab, but now we have electronic devices in our pockets that do all of the work for us. How do these miracle devices do it? Hosted by: Olivia Gordon

You might have heard that exposure to unnatural lights from digital devices can hurt your eyes. But is that true? Hosted by: Stefan Chin

There are a lot of ways to get around in space, from using plain old sunlight to making super-hot plasma. We’ve talked about a lot of propulsion methods over the years, and now, it’s time for some highlights!

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Back in 1862, soldiers fighting in the American Civil War noticed a strange blue glow on their wounds. It took a couple of High School students to figure out what it was.

Taking photos used to require technical knowledge and time in a lab, but now we have electronic devices in our pockets that do all of the work for us. How do these miracle devices do it?

Taking photos used to require technical knowledge and time in a lab, but now we have electronic devices in our pockets that do all of the work for us. How do these miracle devices do it?

The world is full of colors. Almost all of them can be described by a wavelength of visible light, but there are some colors out there that are just in your head!

If you celebrate American Thanksgiving, odds are you're full of food and pretty sleepy right about now. While you drift off for a post-feast nap, enjoy this compilation of episodes covering all kinds of different sleepy, science-y topics!

Fluorescent molecules are useful for a lot more than just making you look cool at your local rave. Fluorescence turns out to be a kind of chemical superpower that lets us tackle all kinds of problems, from solving crimes to saving lives!

Hank goes head-to-head with Minute Physics’ Henry Reich to test their wits about the winter solstice, reindeer, and the science of snow! Chapters View all HANK GREEN 0:20 HENRY REICH 0:28 MAX LOUTZENHEISER 1:03 FLORIAN STINGLMAYR 1:06...

You might know that if you chomp on a Wint-O-Green Lifesaver in a dark room, you can see little blue flashes of light in your mouth. What you might not know is that this is an example of triboluminescence: a fascinating, somewhat...

Some 80 to 90 percent of undersea creatures make light -- and we know very little about how or why. Bioluminescence expert Edith Widder explores this glowing, sparkling, luminous world, sharing glorious images and insight into the unseen...

You've probably heard that some types of light, like the kind that comes from your phone or laptop, can be bad for your sleep if you use them too close to bedtime. But let's be real, nighttime is the best time to binge TV, so are we...

In some parts of the United States, it's said that a green sky means there's a tornado on the way. But while you should probably go inside, things might not necessarily get so bad"

Sometimes, against a uniform, bright background such as a clear sky or a blank computer screen, you might see things floating across your field of vision. What are these moving objects, and how are you seeing them? Michael Mauser...

Just a few meters below the waves, marine biologist and explorer-photographer David Gruber discovered something amazing -- a surprising new range of sea creatures that glow in many colors in the ocean's dim blue light. Join his journey...

Astronomers study a lot of gorgeous things, but nebulae might be the most breathtakingly beautiful of them all. Nebulae are clouds of gas and dust in space. They can glow on their own or reflect light from nearby stars. When they glow...