What’s irrational and never ends? Pi! Hank explains how we need pi to explain some of the most basic but most important principles of the universe, in honor of Pi Day.

every minute, 400 pounds of hydrogen and almost 7 pounds of helium escape from earth's atmosphere into outer space. Astrophysicist Anjali Tripathi studies the phenomenon of atmospheric escape, and in this fascinating and accessible talk,...

How often do we miss asteroids like 2017 OO1, and what are astronomers doing to limit their impact? Meanwhile, distant icy worlds might not look as promising in our search for extraterrestrial life as scientists once thought.

Scientists have discovered over 5,000 exoplanets in the last few decades, but where are the Exo-Earths?

The majority of the universe is made up of a currently mysterious entity that pervades space: dark energy. We don’t know exactly what it is, but we do know that dark energy accelerates the expansion of space. We think this means the...

elon Musk discusses his new project digging tunnels under LA, the latest from Tesla and SpaceX and his motivation for building a future on Mars in conversation with TeD's Head Curator, Chris Anderson.

Lasers are incredible narrow beams of light we can use to do everything from cutting metal to operating on people's eyeballs. But even though we came up with the idea on our own, humans didn’t actually make the first lasers.

Around a quarter of a million years after the Big Bang, the very first molecule, helium hydride was formed. Now scientists have confirmed that molecule is still being made, and they found it with some help from a high flying airplane.

Hank tells us four incredible things about Jupiter's sixth moon, Europa.

In which Hank and John Green teach you about life on Earth. They won't be giving advice on how life should be lived, because this is a history series. Instead, they'll teach you about the earliest forms of life on Earth, and some of the...

Earth is unique in that it's the only planet we know of that can support life. But could there be another planet like ours somewhere far away?

The universe is incredibly old, astoundingly vast and populated by trillions of planets -- so where are all the aliens? Astronomer Stephen Webb has an explanation: we're alone in the universe. In a mind-expanding talk, he spells out the...

My open letter to the universe.

The International Ultraviolet Explorer was the first of its kind, giving us glimpses into phenomena like supernovas and Halley's comet. So why do we hear so little about it?"

SciShow Space tackles a viewer question: Is the Earth getting heavier? The answers -- there's actually more than one -- may surprise you!

Last week scientists announced that they’ve likely identified the very first astrophysical source of high-energy neutrinos.

Over the last few years astronomers have been doing more and more research based on string theory, and thanks to modern telescopes the results are... less than encouraging

Hint: It's not your collection of awesome refrigerator magnets!

If the human body could be distilled down into one molecule, what would our chemical formula be? And WHY is it that way? There’s a whole lot of elements on the periodic table, but life depends on relatively few of them in order to...

The previous videos in this series:

Chapter 1: Why Relativity is
Hard
Chapter 2: Spacetime
Diagrams
Chapter 3: Lorentz T

ransformations

This video is chapter 4 in my series on special relativity, and it...

About 1200 years ago, Earth may have experienced one of the rarest and most powerful cosmic events a planet can be exposed to: a gamma-ray burst. If it did, well, let's just say that we, as living things on Earth, are lucky it wasn't worse.

In 2012, scientists at CERN discovered evidence of the Higgs boson. The what? The Higgs boson is one of two types of fundamental particles and is a particular game-changer in the field of particle physics, proving how particles gain...

You might not want to sign up for the Enceladus Ice Hockey League... And some researchers have an idea that might make the Big Bang model more accurate!

Could human civilization eventually spread across the whole Milky Way galaxy? Could we move beyond our small, blue planet to establish colonies in the multitude of star systems out there? These questions are pretty daunting, but their...