
The show is way out there, way far away. After all, it's in Outer Space. When you look at the night sky on a clear dark night, you can see thousands of stars. There are far more than you could count. And, they are way out there. They are very, very far away. It's about the hardest thing to imagine about space. Let's talk about the nearest star to us, the Sun. If somehow outer space were not an icy cold vacuum with nothing to eat, drink, or breathe, and we could drive there in a car, to get to the Sun at freeway speed of 100 kilometers/hour (61 miles/hour), it would take171 years of driving without stopping to sleep or get gas out in the near nothingness of space. That's just to the Sun. To get to even the closest star, Proxima Centauri, would take 40,000 years. On top of that, most things, billions and billions of stars, are much, much farther away than that! It is just astonishing. How do we know that everything is so far away? We have watched the sky for centuries.
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E11993 · 26m
Things that fly need air. Even though we walk through it, breathe it, and sneeze it, air seems to be a whole bunch of nothing. But air is there, and it's powerful. Balloons inflate because air presses on the insides and outsides of the balloon. Air pressure in tires supports the weight of bikes, buses, trucks, cars, and planes. But air doesn't need to be inside something to exert pressure. Air that moves around pushes, too. What do birds, planes, kites, Frisbees, and helicopters have in common? They fly because moving air creates lift, or a push up. Airplane wings are shaped to push air down. The momentum of the air going down pushes wings up. Air above the wing gets going faster than the air underneath. Fast-moving air zips along, without pushing as hard side to side or up and down. The slow air pushes up from below harder than the fast air pushes down from above ... and you're airborne! Every flying thing, from the tiniest flying insect to the biggest airplane, us
E21993 · 26m
Don't just go with the flow. Settle down on the crust. Imagine a world without any crust. There would be no pies, just goopy filling, no bread, no hamburger buns, and no you or me. That's right. You, and every living thing we know of, live on or in the Earth's crust. And, living things need the Earth's crust to survive. Let's look at the science of the surface. By carefully studying the Earth's surface, scientists have discovered that the Earth is made up of gigantic layers. At the center of the Earth, there is a core – a big ball of solid metal mostly iron. The core is surrounded by a layer of liquid iron and other minerals. We usually just call it the outer core. The next layer, around the outer core is called the mantle. You may have seen a mantle above a fireplace. Well, the mantle is above the Earth's hot core places. The mantle is gooey hot nearly melted rock that flows the way asphalt does on a hot summer day. Scientists often say that the mantle is plastic. It
Breakthrough: The Ideas That Changed the World
2019 · ★ 7.8