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This video is about why it's harder to successfully land spacecraft and landers and rovers on Mars than on Earth, or Venus, or the Moon, or Titan, or asteroids. It all comes down to atmospheric density! When there's no atmosphere, you can do a powered descent in a flimsy tinfoil spacecraft like the Lunar Module, and when there's plenty of atmosphere you can do an unpowered descent via heat shield and parachutes like the space shuttle, Apollo command module, Soyuz, Huygens, etc. But on Mars with its thin air, you have to do both powered & unpowered descent, getting the worst of both worlds.

We're used to thinking hugely well of democracy. But interestingly, one of the wisest people who ever lived, Socrates, had deep suspicions of it.

Glacier ice is weird. It's solid. Solid things aren't supposed to flow. But glacier ice flows like a liquid, and it does that without melting! How is this possible? I traveled to Mendenhall Glacier in Juneau, Alaska to find out.

Chris Atkeson, the creator of Big Hero 6's Baymax, wants to bring soft robots to the world.

Researchers at Stanford University developed a soft, squishy robot that "grows" like a vine and can squeeze through tight spaces. It can also lift heavy objects, which makes it potentially ideal for search-and-rescue operations.

Kaden Casebolt, 5, has Osteogenesis Imperfecta, meaning his bones can break from sneezing. Despite his fragility, the superhero-obsessed boy loves dressing up as his heroes.

Mexico's vast capital - Ciudad de Mexico, the largest city in the Americas - is threatened by a severe water crisis.

In assessing what material things are important and worth paying attention to, we're oddly prejudiced against cheapness - and frustratingly drawn to the expensive, for reasons that don't necessarily stand up to examination.

The giant crack that's been racing across Antarctica Larsen C ice shelf finally met its breaking point between July 10 and 12. The result was an iceberg the size of Delaware and weighing a trillion metric tons.

Why Christopher Nolan is obsessed with Shepard tones.

The philosophy of Kurzgesagt.

One of the key requirements for having a good chance of finding the right partner is not to mind too much being single.

Each year in the United States, players of sports and recreational activities receive between 2.5 and 4 million concussions. How dangerous are all those concussions? The answer is complicated and lies in how the brain responds when something strikes it. Clifford Robbins explains the science behind concussions.

Partners who break up frequently think that the nicest thing to do is to try to remain good friends. But this nice-sounding gesture frequently brings with it unexpected consequences. It may be better to plot a different course.

The Microsoft co-founder imagined much of the tech we use today before it even existed. He shared his thoughts in a 1999 book called "Business @ the Speed of Thought." Here's a quick look at 6 of his predictions that eventually came true, including a device you are probably holding in your hands right now.

They're not just an animal, they're a material. And that's got engineers interested.

Scientists think they've found the molecular basis for organ transplant rejection. Now that we know its cause, could we prevent its effect?